For those of you that have an RS Liberty you will find the following
very
> interesting.... even rex owners may have an interest...afterall it
concerns
> a wrx rear muffler. The reason for below mods, i have family living in
the
> snowy mountains and commute quite regulary from Sydney. My wife did not
like
> the extra noise from my 3" system. ps i have to sit next to her for more
> than 5 hours for this trip.
>
> 1. First before i start, my car: 1992 RS Liberty sedan, has a
complete
> turbo back 3" mrt s/s system fitted. (Great system might i add.) A
'Festo'
> bleed type valve for added boost with a fuel cut defender, resonator
> removed, with air inlet hole increased in the oem filter box. Boost set
at
> 16psi.
> With this setup the car reached an easy16psi boost. (naturaly as that is
> what i set it at)
> I removed the mrt s/s rear muffler and fitted the std RS Liberty muffler
> back on. I purchased an adapter flange from mrt ($20) so the std muffler
> would bolt up to the 3" mrt turbo back system.
> The first thing i noticed.. very quiet.. can hear wind noise again.... not
> that the mrt system was loud by any means. The other thing i noticed is
> how the car lost power. Also boost was now only "just" reaching 14psi.
> Obviously the exhaust restriction, back pressure, has the turbo not
spinning
> as freely, deffinite difference.
>
> 2. Next i purchased a used wrx muffler off mrt, $50. It was off an 11/97
> wrx. The difference between the RS Liberty muffler and the rex muffler was
> immediatley noticeable.
> a) The overall size alone of the wrx muffler is shorter. Also the inlet
pipe
> going into the muffler on the RS is 1 3/4" (45mm) I.D.
> On the rex the I.D. pipe is 2 1/4" (56mm), thats 11mm bigger I.D. for the
> wrx.
> b).The twin outlet pipes on the RS may look like they are 1 5/8"
(40mm)I.D.
> but they are swaged down to 1 1/4" (32mm) near the tips.
> The wrx is 1 5/8" (40mm) with NO swage.
>
> 3. I cut the RS muffler open. it gets worse. The 1 1/4" (32mm) swage at
> the tips is actually the size of both the entire internal outlet pipes.
The
> wrx is 40mm constant right through. This alone gives an I.D increase of
8mm
> on EACH outlet pipe, times this by two, big difference. Not only that but
> in the picture of the wrx muffler, (picture attached) you will see how
the
> gases split in two directions, half the gases flow through the long
internal
> pipe going from chamber 2 to chamber 4 , then back through the hole in the
> seperator (baffle) to chamber 3 etc. On the RS muffler there is NO hole in
> the seperator. The gases enter into chamber 4 with nowhere to go!
> Rediculous!. talk about 'choked' up.
>
> In summary ..... the wrx muffler has a larger inlet pipe by 11mm, better
> flowing internals with the hole in the seperator(baffle), and the two
> internal, leading outlet, pipes are larger by 8mm EACH., I.D.
> 4. So i took the wrx muffler to my local exhaust shop who modified it to
> fit to my Lberty. He cut off the original inlet pipe to the muffler,
(angles
> are different), and made a whole new 2 1/2" pipe welded to the muffler on
> one end and with the mrt adaptor welded to it, to bolt onto my mrt system,
> on the other. Also needed to modify one of the hanger brkts. Cost me $50
for
> the
> whole job.
>
> The results......... my car now boosts again at 16psi and has power again
> ......and is QUIET.
> Overall I think if you own a Liberty RS, a good compromise is to fit a
late
> model wrx rear muffler with a good turbo back system, you will end up with
> good power, std look (chrome outlet on wrx is also better looking than
the
> RS) and is quiet. Maybe someone should do a dyno test on a late model wrx
> keeping the oem muffler but replacing the exhaust from turbo back up to
the
> rear muffler.
> It maybe suprising. For those that want out and out performance obviously
> the rear muffler would help more but by how much ???????
> The Liberty muffler isn't worth the work to modify, Which is what i was
> going to do. I would need to replace the whole internals ..pipes etc..so
> in the bin with that one ......
> Subaru lists the std wrx with a slighty higher output rating than the std
RS
> Liberty, perhaps this muffler mod by subaru is 'part' of the reason for
it.
> Subaru have obviously worked on a less restrictive muffler. No wonder a
rear
> muffler mod on the RS Liberty made such a huge difference. Overall cost,
> muffler $50, flange $20, work $50 , total $120.
> Regards, Rod.
>
>
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RS Liberty muffer/exhaust mods, info
Moderators: Helpinators, Moderators
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Dave C
RS Liberty muffer/exhaust mods, info
Very interesting. I wonder how restrictive my stock US muffler is 
--- In BC-BFLegacyWorks@y..., "Rod" <melrod@o...> wrote:
> For those of you that have an RS Liberty you will find the
following
> very
> > interesting.... even rex owners may have an interest...afterall it
> concerns
> > a wrx rear muffler. The reason for below mods, i have family
living in
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--- In BC-BFLegacyWorks@y..., "Rod" <melrod@o...> wrote:
> For those of you that have an RS Liberty you will find the
following
> very
> > interesting.... even rex owners may have an interest...afterall it
> concerns
> > a wrx rear muffler. The reason for below mods, i have family
living in
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Ross
RS Liberty muffer/exhaust mods, info
Rod, I have an RS Liberty with standard exhaust system. Everything else on the car is also stock. I would like to increase power by upgrading the exhaust system, but would like to keep the car quiet. Based on your experience, what do you think I should do? Should I replace my RS muffler with a WRX muffler? What would be required to do this, as in piping mods etc. Does anyone else have similar experience?
I also find it interesting that perhaps the standard power output of the WRX may be higher than the RS due to the exhaust. Does that mean the MY99/00WRX, with 160kw had a better muffler than earlier model WRX with 155kw?
Cheers
Ross
----- Original Message -----
From: Rod <mailto:melrod@optusnet.com.au>
To: wrx@yahoogroups.com
Cc: BC-BFLegacyWorks@yahoogroups.com
Sent: Thursday, 1 February 2001 6:30 PM
Subject: [BC-BFLegacyWorks] Fw: RS Liberty muffer/exhaust mods, info
For those of you that have an RS Liberty you will find the following
very
> interesting.... even rex owners may have an interest...afterall it
concerns
> a wrx rear muffler. The reason for below mods, i have family living in
the
> snowy mountains and commute quite regulary from Sydney. My wife did not
like
> the extra noise from my 3" system. ps i have to sit next to her for more
> than 5 hours for this trip.
>
> 1. First before i start, my car: 1992 RS Liberty sedan, has a
complete
> turbo back 3" mrt s/s system fitted. (Great system might i add.) A
'Festo'
> bleed type valve for added boost with a fuel cut defender, resonator
> removed, with air inlet hole increased in the oem filter box. Boost set
at
> 16psi.
> With this setup the car reached an easy16psi boost. (naturaly as that is
> what i set it at)
> I removed the mrt s/s rear muffler and fitted the std RS Liberty muffler
> back on. I purchased an adapter flange from mrt ($20) so the std muffler
> would bolt up to the 3" mrt turbo back system.
> The first thing i noticed.. very quiet.. can hear wind noise again.... not
> that the mrt system was loud by any means. The other thing i noticed is
> how the car lost power. Also boost was now only "just" reaching 14psi.
> Obviously the exhaust restriction, back pressure, has the turbo not
spinning
> as freely, deffinite difference.
>
> 2. Next i purchased a used wrx muffler off mrt, $50. It was off an 11/97
> wrx. The difference between the RS Liberty muffler and the rex muffler was
> immediatley noticeable.
> a) The overall size alone of the wrx muffler is shorter. Also the inlet
pipe
> going into the muffler on the RS is 1 3/4" (45mm) I.D.
> On the rex the I.D. pipe is 2 1/4" (56mm), thats 11mm bigger I.D. for the
> wrx.
> b).The twin outlet pipes on the RS may look like they are 1 5/8"
(40mm)I.D.
> but they are swaged down to 1 1/4" (32mm) near the tips.
> The wrx is 1 5/8" (40mm) with NO swage.
>
> 3. I cut the RS muffler open. it gets worse. The 1 1/4" (32mm) swage at
> the tips is actually the size of both the entire internal outlet pipes.
The
> wrx is 40mm constant right through. This alone gives an I.D increase of
8mm
> on EACH outlet pipe, times this by two, big difference. Not only that but
> in the picture of the wrx muffler, (picture attached) you will see how
the
> gases split in two directions, half the gases flow through the long
internal
> pipe going from chamber 2 to chamber 4 , then back through the hole in the
> seperator (baffle) to chamber 3 etc. On the RS muffler there is NO hole in
> the seperator. The gases enter into chamber 4 with nowhere to go!
> Rediculous!. talk about 'choked' up.
>
> In summary ..... the wrx muffler has a larger inlet pipe by 11mm, better
> flowing internals with the hole in the seperator(baffle), and the two
> internal, leading outlet, pipes are larger by 8mm EACH., I.D.
> 4. So i took the wrx muffler to my local exhaust shop who modified it to
> fit to my Lberty. He cut off the original inlet pipe to the muffler,
(angles
> are different), and made a whole new 2 1/2" pipe welded to the muffler on
> one end and with the mrt adaptor welded to it, to bolt onto my mrt system,
> on the other. Also needed to modify one of the hanger brkts. Cost me $50
for
> the
> whole job.
>
> The results......... my car now boosts again at 16psi and has power again
> ......and is QUIET.
> Overall I think if you own a Liberty RS, a good compromise is to fit a
late
> model wrx rear muffler with a good turbo back system, you will end up with
> good power, std look (chrome outlet on wrx is also better looking than
the
> RS) and is quiet. Maybe someone should do a dyno test on a late model wrx
> keeping the oem muffler but replacing the exhaust from turbo back up to
the
> rear muffler.
> It maybe suprising. For those that want out and out performance obviously
> the rear muffler would help more but by how much ???????
> The Liberty muffler isn't worth the work to modify, Which is what i was
> going to do. I would need to replace the whole internals ..pipes etc..so
> in the bin with that one ......
> Subaru lists the std wrx with a slighty higher output rating than the std
RS
> Liberty, perhaps this muffler mod by subaru is 'part' of the reason for
it.
> Subaru have obviously worked on a less restrictive muffler. No wonder a
rear
> muffler mod on the RS Liberty made such a huge difference. Overall cost,
> muffler $50, flange $20, work $50 , total $120.
> Regards, Rod.
>
>
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I also find it interesting that perhaps the standard power output of the WRX may be higher than the RS due to the exhaust. Does that mean the MY99/00WRX, with 160kw had a better muffler than earlier model WRX with 155kw?
Cheers
Ross
----- Original Message -----
From: Rod <mailto:melrod@optusnet.com.au>
To: wrx@yahoogroups.com
Cc: BC-BFLegacyWorks@yahoogroups.com
Sent: Thursday, 1 February 2001 6:30 PM
Subject: [BC-BFLegacyWorks] Fw: RS Liberty muffer/exhaust mods, info
For those of you that have an RS Liberty you will find the following
very
> interesting.... even rex owners may have an interest...afterall it
concerns
> a wrx rear muffler. The reason for below mods, i have family living in
the
> snowy mountains and commute quite regulary from Sydney. My wife did not
like
> the extra noise from my 3" system. ps i have to sit next to her for more
> than 5 hours for this trip.
>
> 1. First before i start, my car: 1992 RS Liberty sedan, has a
complete
> turbo back 3" mrt s/s system fitted. (Great system might i add.) A
'Festo'
> bleed type valve for added boost with a fuel cut defender, resonator
> removed, with air inlet hole increased in the oem filter box. Boost set
at
> 16psi.
> With this setup the car reached an easy16psi boost. (naturaly as that is
> what i set it at)
> I removed the mrt s/s rear muffler and fitted the std RS Liberty muffler
> back on. I purchased an adapter flange from mrt ($20) so the std muffler
> would bolt up to the 3" mrt turbo back system.
> The first thing i noticed.. very quiet.. can hear wind noise again.... not
> that the mrt system was loud by any means. The other thing i noticed is
> how the car lost power. Also boost was now only "just" reaching 14psi.
> Obviously the exhaust restriction, back pressure, has the turbo not
spinning
> as freely, deffinite difference.
>
> 2. Next i purchased a used wrx muffler off mrt, $50. It was off an 11/97
> wrx. The difference between the RS Liberty muffler and the rex muffler was
> immediatley noticeable.
> a) The overall size alone of the wrx muffler is shorter. Also the inlet
pipe
> going into the muffler on the RS is 1 3/4" (45mm) I.D.
> On the rex the I.D. pipe is 2 1/4" (56mm), thats 11mm bigger I.D. for the
> wrx.
> b).The twin outlet pipes on the RS may look like they are 1 5/8"
(40mm)I.D.
> but they are swaged down to 1 1/4" (32mm) near the tips.
> The wrx is 1 5/8" (40mm) with NO swage.
>
> 3. I cut the RS muffler open. it gets worse. The 1 1/4" (32mm) swage at
> the tips is actually the size of both the entire internal outlet pipes.
The
> wrx is 40mm constant right through. This alone gives an I.D increase of
8mm
> on EACH outlet pipe, times this by two, big difference. Not only that but
> in the picture of the wrx muffler, (picture attached) you will see how
the
> gases split in two directions, half the gases flow through the long
internal
> pipe going from chamber 2 to chamber 4 , then back through the hole in the
> seperator (baffle) to chamber 3 etc. On the RS muffler there is NO hole in
> the seperator. The gases enter into chamber 4 with nowhere to go!
> Rediculous!. talk about 'choked' up.
>
> In summary ..... the wrx muffler has a larger inlet pipe by 11mm, better
> flowing internals with the hole in the seperator(baffle), and the two
> internal, leading outlet, pipes are larger by 8mm EACH., I.D.
> 4. So i took the wrx muffler to my local exhaust shop who modified it to
> fit to my Lberty. He cut off the original inlet pipe to the muffler,
(angles
> are different), and made a whole new 2 1/2" pipe welded to the muffler on
> one end and with the mrt adaptor welded to it, to bolt onto my mrt system,
> on the other. Also needed to modify one of the hanger brkts. Cost me $50
for
> the
> whole job.
>
> The results......... my car now boosts again at 16psi and has power again
> ......and is QUIET.
> Overall I think if you own a Liberty RS, a good compromise is to fit a
late
> model wrx rear muffler with a good turbo back system, you will end up with
> good power, std look (chrome outlet on wrx is also better looking than
the
> RS) and is quiet. Maybe someone should do a dyno test on a late model wrx
> keeping the oem muffler but replacing the exhaust from turbo back up to
the
> rear muffler.
> It maybe suprising. For those that want out and out performance obviously
> the rear muffler would help more but by how much ???????
> The Liberty muffler isn't worth the work to modify, Which is what i was
> going to do. I would need to replace the whole internals ..pipes etc..so
> in the bin with that one ......
> Subaru lists the std wrx with a slighty higher output rating than the std
RS
> Liberty, perhaps this muffler mod by subaru is 'part' of the reason for
it.
> Subaru have obviously worked on a less restrictive muffler. No wonder a
rear
> muffler mod on the RS Liberty made such a huge difference. Overall cost,
> muffler $50, flange $20, work $50 , total $120.
> Regards, Rod.
>
>
To unsubscribe from this group, send an email to:
BC-BFLegacyWorks-unsubscribe@egroups.com
<http://rd.yahoo.com/M=176325.1307935.29 ... .yahoo.com> <http://rd.yahoo.com/M=176325.1307935.29 ... omains.com>
www.
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-
Rod
RS Liberty muffer/exhaust mods, info
Ross,
There are two restrictions in the exhaust system. The major one, as you know by my experience, is the rear muffler. It's a pig. The other is the flange on the turbo outlet. If I was to start again, first I would purchase a good second hand wrx rear muffler. Take it to an exhaust shop and get them to cut the inlet pipe off at the muffler. Then make up a new 2 1/2" pipe, weld it to the muffler and flange to bolt up to the oem mount. One hanger bracket on the wrx muffler is different. You will see this when you take the RS muffler off, modify this to match the support rubber. Done. To go one step better, my choice, get a full 3" turbo back exhaust to bolt up to your wrx muffler, a good down pipe design is of coarse mandatory or it defeats the purpose. This full system is the way to go. You will have much better flow, std look, and sounds std.
Of coarse before performing any mods on a turbo car you should have a boost gauge installed so as to monitor the diference, see whats happenning.
With this exhaust do the inlet mods, very simple, and you will be able to run at 15-16 psi boost. (whether you use bleed valve, as i have, or other setup.Yours have an intercooler?) With these three mods, ie full exhaust, inlet, higher boost, you will think your in a different car. ......huge difference in power. Drives heaps better also.
I think the later model wrx has a higher power output rating because it runs a slightly higher boost. I cannot say whether the wrx muffler has changed from 94 onwards but the one i used was off an 11/98 model. It looks exactly like the one in the picture attachment. If you want more info, just ask.
Regards, Rod
To: BC-BFLegacyWorks@yahoogroups.com
Sent: Thursday, February 01, 2001 10:15 PM
Subject: Re: [BC-BFLegacyWorks] Fw: RS Liberty muffer/exhaust mods, info
Rod, I have an RS Liberty with standard exhaust system. Everything else on the car is also stock. I would like to increase power by upgrading the exhaust system, but would like to keep the car quiet. Based on your experience, what do you think I should do? Should I replace my RS muffler with a WRX muffler? What would be required to do this, as in piping mods etc. Does anyone else have similar experience?
I also find it interesting that perhaps the standard power output of the WRX may be higher than the RS due to the exhaust. Does that mean the MY99/00WRX, with 160kw had a better muffler than earlier model WRX with 155kw?
Cheers
Ross
----- Original Message -----
From: Rod <mailto:melrod@optusnet.com.au>
To: wrx@yahoogroups.com
Cc: BC-BFLegacyWorks@yahoogroups.com
Sent: Thursday, 1 February 2001 6:30 PM
Subject: [BC-BFLegacyWorks] Fw: RS Liberty muffer/exhaust mods, info
For those of you that have an RS Liberty you will find the following
very
> interesting.... even rex owners may have an interest...afterall it
concerns
> a wrx rear muffler. The reason for below mods, i have family living in
the
> snowy mountains and commute quite regulary from Sydney. My wife did not
like
> the extra noise from my 3" system. ps i have to sit next to her for more
> than 5 hours for this trip.
>
> 1. First before i start, my car: 1992 RS Liberty sedan, has a
complete
> turbo back 3" mrt s/s system fitted. (Great system might i add.) A
'Festo'
> bleed type valve for added boost with a fuel cut defender, resonator
> removed, with air inlet hole increased in the oem filter box. Boost set
at
> 16psi.
> With this setup the car reached an easy16psi boost. (naturaly as that is
> what i set it at)
> I removed the mrt s/s rear muffler and fitted the std RS Liberty muffler
> back on. I purchased an adapter flange from mrt ($20) so the std muffler
> would bolt up to the 3" mrt turbo back system.
> The first thing i noticed.. very quiet.. can hear wind noise again.... not
> that the mrt system was loud by any means. The other thing i noticed is
> how the car lost power. Also boost was now only "just" reaching 14psi.
> Obviously the exhaust restriction, back pressure, has the turbo not
spinning
> as freely, deffinite difference.
>
> 2. Next i purchased a used wrx muffler off mrt, $50. It was off an 11/97
> wrx. The difference between the RS Liberty muffler and the rex muffler was
> immediatley noticeable.
> a) The overall size alone of the wrx muffler is shorter. Also the inlet
pipe
> going into the muffler on the RS is 1 3/4" (45mm) I.D.
> On the rex the I.D. pipe is 2 1/4" (56mm), thats 11mm bigger I.D. for the
> wrx.
> b).The twin outlet pipes on the RS may look like they are 1 5/8"
(40mm)I.D.
> but they are swaged down to 1 1/4" (32mm) near the tips.
> The wrx is 1 5/8" (40mm) with NO swage.
>
> 3. I cut the RS muffler open. it gets worse. The 1 1/4" (32mm) swage at
> the tips is actually the size of both the entire internal outlet pipes.
The
> wrx is 40mm constant right through. This alone gives an I.D increase of
8mm
> on EACH outlet pipe, times this by two, big difference. Not only that but
> in the picture of the wrx muffler, (picture attached) you will see how
the
> gases split in two directions, half the gases flow through the long
internal
> pipe going from chamber 2 to chamber 4 , then back through the hole in the
> seperator (baffle) to chamber 3 etc. On the RS muffler there is NO hole in
> the seperator. The gases enter into chamber 4 with nowhere to go!
> Rediculous!. talk about 'choked' up.
>
> In summary ..... the wrx muffler has a larger inlet pipe by 11mm, better
> flowing internals with the hole in the seperator(baffle), and the two
> internal, leading outlet, pipes are larger by 8mm EACH., I.D.
> 4. So i took the wrx muffler to my local exhaust shop who modified it to
> fit to my Lberty. He cut off the original inlet pipe to the muffler,
(angles
> are different), and made a whole new 2 1/2" pipe welded to the muffler on
> one end and with the mrt adaptor welded to it, to bolt onto my mrt system,
> on the other. Also needed to modify one of the hanger brkts. Cost me $50
for
> the
> whole job.
>
> The results......... my car now boosts again at 16psi and has power again
> ......and is QUIET.
> Overall I think if you own a Liberty RS, a good compromise is to fit a
late
> model wrx rear muffler with a good turbo back system, you will end up with
> good power, std look (chrome outlet on wrx is also better looking than
the
> RS) and is quiet. Maybe someone should do a dyno test on a late model wrx
> keeping the oem muffler but replacing the exhaust from turbo back up to
the
> rear muffler.
> It maybe suprising. For those that want out and out performance obviously
> the rear muffler would help more but by how much ???????
> The Liberty muffler isn't worth the work to modify, Which is what i was
> going to do. I would need to replace the whole internals ..pipes etc..so
> in the bin with that one ......
> Subaru lists the std wrx with a slighty higher output rating than the std
RS
> Liberty, perhaps this muffler mod by subaru is 'part' of the reason for
it.
> Subaru have obviously worked on a less restrictive muffler. No wonder a
rear
> muffler mod on the RS Liberty made such a huge difference. Overall cost,
> muffler $50, flange $20, work $50 , total $120.
> Regards, Rod.
>
>
To unsubscribe from this group, send an email to:
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There are two restrictions in the exhaust system. The major one, as you know by my experience, is the rear muffler. It's a pig. The other is the flange on the turbo outlet. If I was to start again, first I would purchase a good second hand wrx rear muffler. Take it to an exhaust shop and get them to cut the inlet pipe off at the muffler. Then make up a new 2 1/2" pipe, weld it to the muffler and flange to bolt up to the oem mount. One hanger bracket on the wrx muffler is different. You will see this when you take the RS muffler off, modify this to match the support rubber. Done. To go one step better, my choice, get a full 3" turbo back exhaust to bolt up to your wrx muffler, a good down pipe design is of coarse mandatory or it defeats the purpose. This full system is the way to go. You will have much better flow, std look, and sounds std.
Of coarse before performing any mods on a turbo car you should have a boost gauge installed so as to monitor the diference, see whats happenning.
With this exhaust do the inlet mods, very simple, and you will be able to run at 15-16 psi boost. (whether you use bleed valve, as i have, or other setup.Yours have an intercooler?) With these three mods, ie full exhaust, inlet, higher boost, you will think your in a different car. ......huge difference in power. Drives heaps better also.
I think the later model wrx has a higher power output rating because it runs a slightly higher boost. I cannot say whether the wrx muffler has changed from 94 onwards but the one i used was off an 11/98 model. It looks exactly like the one in the picture attachment. If you want more info, just ask.
Regards, Rod
To: BC-BFLegacyWorks@yahoogroups.com
Sent: Thursday, February 01, 2001 10:15 PM
Subject: Re: [BC-BFLegacyWorks] Fw: RS Liberty muffer/exhaust mods, info
Rod, I have an RS Liberty with standard exhaust system. Everything else on the car is also stock. I would like to increase power by upgrading the exhaust system, but would like to keep the car quiet. Based on your experience, what do you think I should do? Should I replace my RS muffler with a WRX muffler? What would be required to do this, as in piping mods etc. Does anyone else have similar experience?
I also find it interesting that perhaps the standard power output of the WRX may be higher than the RS due to the exhaust. Does that mean the MY99/00WRX, with 160kw had a better muffler than earlier model WRX with 155kw?
Cheers
Ross
----- Original Message -----
From: Rod <mailto:melrod@optusnet.com.au>
To: wrx@yahoogroups.com
Cc: BC-BFLegacyWorks@yahoogroups.com
Sent: Thursday, 1 February 2001 6:30 PM
Subject: [BC-BFLegacyWorks] Fw: RS Liberty muffer/exhaust mods, info
For those of you that have an RS Liberty you will find the following
very
> interesting.... even rex owners may have an interest...afterall it
concerns
> a wrx rear muffler. The reason for below mods, i have family living in
the
> snowy mountains and commute quite regulary from Sydney. My wife did not
like
> the extra noise from my 3" system. ps i have to sit next to her for more
> than 5 hours for this trip.
>
> 1. First before i start, my car: 1992 RS Liberty sedan, has a
complete
> turbo back 3" mrt s/s system fitted. (Great system might i add.) A
'Festo'
> bleed type valve for added boost with a fuel cut defender, resonator
> removed, with air inlet hole increased in the oem filter box. Boost set
at
> 16psi.
> With this setup the car reached an easy16psi boost. (naturaly as that is
> what i set it at)
> I removed the mrt s/s rear muffler and fitted the std RS Liberty muffler
> back on. I purchased an adapter flange from mrt ($20) so the std muffler
> would bolt up to the 3" mrt turbo back system.
> The first thing i noticed.. very quiet.. can hear wind noise again.... not
> that the mrt system was loud by any means. The other thing i noticed is
> how the car lost power. Also boost was now only "just" reaching 14psi.
> Obviously the exhaust restriction, back pressure, has the turbo not
spinning
> as freely, deffinite difference.
>
> 2. Next i purchased a used wrx muffler off mrt, $50. It was off an 11/97
> wrx. The difference between the RS Liberty muffler and the rex muffler was
> immediatley noticeable.
> a) The overall size alone of the wrx muffler is shorter. Also the inlet
pipe
> going into the muffler on the RS is 1 3/4" (45mm) I.D.
> On the rex the I.D. pipe is 2 1/4" (56mm), thats 11mm bigger I.D. for the
> wrx.
> b).The twin outlet pipes on the RS may look like they are 1 5/8"
(40mm)I.D.
> but they are swaged down to 1 1/4" (32mm) near the tips.
> The wrx is 1 5/8" (40mm) with NO swage.
>
> 3. I cut the RS muffler open. it gets worse. The 1 1/4" (32mm) swage at
> the tips is actually the size of both the entire internal outlet pipes.
The
> wrx is 40mm constant right through. This alone gives an I.D increase of
8mm
> on EACH outlet pipe, times this by two, big difference. Not only that but
> in the picture of the wrx muffler, (picture attached) you will see how
the
> gases split in two directions, half the gases flow through the long
internal
> pipe going from chamber 2 to chamber 4 , then back through the hole in the
> seperator (baffle) to chamber 3 etc. On the RS muffler there is NO hole in
> the seperator. The gases enter into chamber 4 with nowhere to go!
> Rediculous!. talk about 'choked' up.
>
> In summary ..... the wrx muffler has a larger inlet pipe by 11mm, better
> flowing internals with the hole in the seperator(baffle), and the two
> internal, leading outlet, pipes are larger by 8mm EACH., I.D.
> 4. So i took the wrx muffler to my local exhaust shop who modified it to
> fit to my Lberty. He cut off the original inlet pipe to the muffler,
(angles
> are different), and made a whole new 2 1/2" pipe welded to the muffler on
> one end and with the mrt adaptor welded to it, to bolt onto my mrt system,
> on the other. Also needed to modify one of the hanger brkts. Cost me $50
for
> the
> whole job.
>
> The results......... my car now boosts again at 16psi and has power again
> ......and is QUIET.
> Overall I think if you own a Liberty RS, a good compromise is to fit a
late
> model wrx rear muffler with a good turbo back system, you will end up with
> good power, std look (chrome outlet on wrx is also better looking than
the
> RS) and is quiet. Maybe someone should do a dyno test on a late model wrx
> keeping the oem muffler but replacing the exhaust from turbo back up to
the
> rear muffler.
> It maybe suprising. For those that want out and out performance obviously
> the rear muffler would help more but by how much ???????
> The Liberty muffler isn't worth the work to modify, Which is what i was
> going to do. I would need to replace the whole internals ..pipes etc..so
> in the bin with that one ......
> Subaru lists the std wrx with a slighty higher output rating than the std
RS
> Liberty, perhaps this muffler mod by subaru is 'part' of the reason for
it.
> Subaru have obviously worked on a less restrictive muffler. No wonder a
rear
> muffler mod on the RS Liberty made such a huge difference. Overall cost,
> muffler $50, flange $20, work $50 , total $120.
> Regards, Rod.
>
>
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