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#downstream second cat removal

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 Post subject: downstream second cat removal
PostPosted: Fri Jul 11, 2014 8:35 pm 
In Neutral
Joined: Sat May 10, 2014 3:40 pm
Posts: 13
I have read the upstream 2-into-1 catalytic converters should be kept what about the second downstream catalytic converter any better benefits from removing it?


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 Post subject: Re: downstream second cat removal
PostPosted: Sun Jul 13, 2014 4:52 am 
Fifth Gear
Joined: Fri May 04, 2007 4:09 pm
Posts: 2264
Location: N. ID
Hi,
Depends on your mods. I recently removed mine as part of a 3" exhaust upgrade and my dyno #'s definitely went up. But I'm also running a bigger turbo/injectors/more boost.
TD

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Turbo Subies:
'87 GL-10 Turbo 4WD Wagon (pre-Loyale) - SOLD
'90 BJ, EJ22T/DOHC and 5-speed swap - SOLD
'04 FXT, Forged internals, VF39, STI TMIC, Cobb AP- SOLD
'93 Legacy SS - 5-speed, SOLD :-(
'02 WRX GG-SOLD
'96 BD - turbo'd-SOLD


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 Post subject: Re: downstream second cat removal
PostPosted: Sun Jul 13, 2014 7:00 am 
Third Gear
Joined: Wed Oct 26, 2011 7:02 am
Posts: 892
Location: Anchorage,Alaska
I removed mine also when installed stainless headers.

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Charles

90' White/Gray Outback DD workhorse (670,xxx) miles
92' Onyx Metallic (430,xxx) Wife's DD
68' Barracuda formula S 340 4spd coupe (ongoing project)
66' Mustang 2+2 4spd wife's (ongoing project)


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 Post subject: Re: downstream second cat removal
PostPosted: Mon Jul 14, 2014 1:20 pm 
Fifth Gear
Joined: Fri Jun 20, 2008 8:17 am
Posts: 6301
Location: Lakewood, Wa 98439
haven't had a cat since 2006

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91 L-TW Wagon with a full Swap -RIP
92 SS Prefaced, GD dash swapped, 22T/205 Hybrid 20 psi - BEAST!
93 SS Bone Stock Gone!
94 TW Bone Stock Gone!
91 SS 4EAT Sold!
98 LGT 4EAT
98 LGT Wagon 4EAT


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 Post subject: Re: downstream second cat removal
PostPosted: Wed Jul 16, 2014 2:29 am 
Moderator
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Joined: Tue Aug 25, 2009 7:52 am
Posts: 4806
Location: Des Moines, Wa
I don't think removing the second cat on a stock engine setup will make a huge difference in the scheme of things, but if you have more upgrades planned for later I don't think it could hurt.

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1992 Legacy SS 5mt, build in progress


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 Post subject: Re: downstream second cat removal
PostPosted: Sat Sep 13, 2014 1:46 pm 
First Gear
Joined: Wed Mar 10, 2010 11:37 pm
Posts: 111
When the 2nd cat is removed, what happens to the oxygen sensor? Just take it off?


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 Post subject: Re: downstream second cat removal
PostPosted: Sat Sep 13, 2014 1:59 pm 
Fifth Gear
Joined: Fri May 04, 2007 4:09 pm
Posts: 2264
Location: N. ID
There is no O2 sensor in the second cat on the first GEN legacies just up by the turbo.
Td

_________________
Turbo Subies:
'87 GL-10 Turbo 4WD Wagon (pre-Loyale) - SOLD
'90 BJ, EJ22T/DOHC and 5-speed swap - SOLD
'04 FXT, Forged internals, VF39, STI TMIC, Cobb AP- SOLD
'93 Legacy SS - 5-speed, SOLD :-(
'02 WRX GG-SOLD
'96 BD - turbo'd-SOLD


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 Post subject: Re: downstream second cat removal
PostPosted: Fri Jan 16, 2015 11:02 pm 
First Gear
Joined: Thu Sep 18, 2014 5:12 pm
Posts: 162
Location: SF Bay Area, CA
Does anyone know what the size and thread pitch is for the factory o2 sensor? I need to add a bung at the stock location on my newly purchased Invidia Bellmouth Catless DP.


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 Post subject: Re: downstream second cat removal
PostPosted: Sat Jan 17, 2015 4:46 pm 
Fifth Gear
Joined: Fri Jun 20, 2008 8:17 am
Posts: 6301
Location: Lakewood, Wa 98439
They're mostly the same. Any exhaust shop will have them for around 10 bucks.

_________________
91 L-TW Wagon with a full Swap -RIP
92 SS Prefaced, GD dash swapped, 22T/205 Hybrid 20 psi - BEAST!
93 SS Bone Stock Gone!
94 TW Bone Stock Gone!
91 SS 4EAT Sold!
98 LGT 4EAT
98 LGT Wagon 4EAT


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 Post subject: Re: downstream second cat removal
PostPosted: Sat Jan 17, 2015 6:34 pm 
First Gear
Joined: Thu Sep 18, 2014 5:12 pm
Posts: 162
Location: SF Bay Area, CA
Got it thanks. It appears that the standard size is M18x1.5.


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