My turbo back story...I installed one today.

Matt Monson · Post by **Matt Monson** » Sat Dec 20, 2003 2:32 am

Last week I picked up a PDM divorced wastegate DP used. 2.5" turbo outlet and a 1.75 wastegate outlet feeding down into a 2.5" pipe. Some of you thought it would mate to the stock mid-pipe, but noone had ever done it.

So, being the learn be doing guy that I am, I decide to go for it. Breaking loose a 95k mi exhaust is hard work. I got it off in about three hours yesterday finishing the removal by headlamp after dark. I started to hang the DP this am, and found it 2" too long for the stock midpipe/cat.

You all had also said that a WRX mid-pipe(I have my gf's complete stock '04 turbo back) needed extending to work. I figure I will check it out. Of course the Legacy's mid-pipe bolts are rotten and won't come off. So I remove the whole exhaust, get the bolts off and rehang the muffler. It turns out the midpipe (which is cat-less)is about 3" short but will hang on the stock flange and mate to the muffler. So I call Ken's Muffler, which the local SCCA guys recommended. He says about $100 to extend the pipe and can do it this afternoon. Oh, and the DP mount is off by about a half inch from the hanger. They had to move that flange too. So I wire it up for the drive to Ken's with just the DP. Damn that shizzat was LOUD!!! I thought my dash was gonna rattle apart!

Marco, at Ken's takes a look at what I want to do and he says,"and where's your cat?" I tell him it is temporary and that I will get one when I do the real work. They start cutting apart the WRX midpipe and we go indside. I ask him what a highflow cat would add to the deal. He says $165 I say,"do it!". So, out the door for $225 plus the cost of the DP $250 and I got my Turbo-back. It is a 2.5" flange feeding into the cat that comes out the other side on a 2.25" WRX midpipe that hangs on the stock hanger and mates to the stock muffler. I will do the muffler when cash allows, but for now it sounds real nice just as it is. I will post pics in a few days when my GF gets here with her digi cam.

Spool up is about 500rpm lower around 2500rpm. It shoots all the way to redline and boost pegs at 11psi (remember I am at 5000ft). For some reason it shifts later and literally goes almost to 6500 rpm before the EAT shifts. I haven't installed the Hallman MBC, and am now afraid to since I won't do the IC until I do the real build.

So, in case anyone wonders in the future...

NO, a WRX stock downpipe is NOT a direct replacement for a Legacy DP.
This also means that aftermarket DP's will not fit. They hang fine but are about 2" too long for the stock midpipe. Unless you have a DP specifically designed for the Legacy, you will need to get the midpipe done custom at the same time. No doing this parts and pieces...

evolutionmovement · Post by **evolutionmovement** » Sat Dec 20, 2003 2:44 am

Excellent post! That's great toknow for us guys who have to do this stuff on the cheap.

Steve

Matt Monson · Post by **Matt Monson** » Sat Dec 20, 2003 2:55 am

I wanted to call it a Ghetto back but my GF said it wasn't ghetto because of the DP. So i call it my trailer trash turbo-back, or T3 for short.

vrg3 · Post by **vrg3** » Sat Dec 20, 2003 2:57 am

It's ghetto-fabulous!

evolutionmovement · Post by **evolutionmovement** » Sat Dec 20, 2003 3:03 am

Vrg3, did you get that expression from the Fab 5?

Steve

vrg3 · Post by **vrg3** » Sat Dec 20, 2003 3:14 am

I have no idea where I got that expression... been using it almost as long as I've been talking... :)

ciper · Post by **ciper** » Sat Dec 20, 2003 4:11 am

If I remember right Subiekid has a 95 legacy with a 92 legacy turbo engine in it. He had an image showing the turbo DP to be short on his stock exhaust.

How far back in the exhaust is the cat? Whats it next to?

Matt Monson · Post by **Matt Monson** » Sat Dec 20, 2003 8:30 pm

The cat is almost in the dead center of the car. The DP ends and then there is about 1.5ft of 2.5" pipe before the cat. Then like 2 ft of WRX pipe and the stock muffler...

One other thing. I haven't extended the O2 sensor, so I am running with the bung open for a day or two. It has CEL'd twice, but it goes off when I turn off the car and doesn't send it into limp...

Matt Monson · Post by **Matt Monson** » Sat Dec 20, 2003 8:31 pm

ciper wrote:If I remember right Subiekid has a 95 legacy with a 92 legacy turbo engine in it. He had an image showing the turbo DP to be short on his stock exhaust.

How far back in the exhaust is the cat? Whats it next to?

Remember that the '95 is the new chassis. My remarks only apply to a BF chassis from 90-94...

ciper · Post by **ciper** » Tue Dec 23, 2003 12:47 am

I understand, I was adding to the discussion of DP compatibility.

Matt Monson · Post by **Matt Monson** » Wed Dec 24, 2003 3:44 am

pics for your viewing pleasure...

Nigel · Post by **Nigel** » Fri Dec 26, 2003 2:22 am

I'm confused... or maybe just lucky... I just picked up a bellmouthed DP, and I'm just eyeballing it, but it looks like it's the right length to bolt right up to the cat on the stock mid-pipe. This isn't supposed to be the case, right? It looks like it's maybe a 1/2" longer, but there should be enough play to push the midpipe/muffer back a 1/2". I haven't installed it yet because I want to have an O2 bung welded on near the stock location (just behind the turbo). It has one down by the cat, and I don't want to run wires all the way down there.

Anyway, it looks like it should bolt right up. It even tapers down to the stock pipe diameter at the cat. I bought the pipe used as the third owner. The PO wanted to use it for a non-subaru application, so he didn't know anything about it other than it was for a WRX. I looked at all the pictures I could find on-line of WRX downpipes, but I can't find one that looks exactly like this.

I'll let you all know how it fits once I get the bung welded on. Should be in a few weeks...

Nigel
'94 Legacy Turbo
'73 Datsun 240Z Turbo

Matt Monson · Post by **Matt Monson** » Fri Dec 26, 2003 4:19 am

I think your eyeball may be off. I now have both the stock '04 WRX DP and the Legacy stock DP on my balcony. They are definitely significantly different. My eyeball said the replacement (which identically matches the WRX DP in dimensions) would fit no problem. Only once I went to the trouble of hanging it did I become sure I wasn't going tp be able to use the stock mid-pipe.

But another way you can "ghetto" address the problem is to cut a couple inches off the stock mid-pipe behind the cat, since the cat is right at the flange on the stock one. That brings up another point, unless your DP is designed for that flared mouth flange on the stock mid-pipe, you will want to seriously consider changing the flange. Take a look at my pics. I got a flat mouthed flange installed on the custom mid-pipe to be sure of a good seal.

Nigel · Post by **Nigel** » Fri Dec 26, 2003 5:49 am

It's quite possible I'm wrong. I'm really tempted to pull the stock dp just to find out. But if I'm right, I'd rather just do this once, so I think I'll wait 'till I get the bung welded on before I try. I measured the distance from the the rear flange of the dp to the lower mounting bracket that bolts to the trany on both dp's and they're within a 1/2 of eachother. Is the WRX dp mount to the trany 2" farther back? The impression I got from your write-up was that it's only about a 1/2" off. Oh yeah, the mating flange to the cat on my new dp uses the same gasket (wire mesh cone), so I think they'll match up ok.

Damn! Why couldn't it already have the O2 bung where I want it so I could put an end to the guessing and just install it

Nigel
'94 Legacy Turbo
'73 Datsun 240Z Turbo

Matt Monson · Post by **Matt Monson** » Fri Dec 26, 2003 5:36 pm

The DP mount on both cars was basically in the same place. It was half an inch off to the side and needed to be lengthened as I couldn't bend the flex joint in the DP far enough to get it into the little cradle on the mount. All of the extra length was after the hanger...

Matt Monson · Post by **Matt Monson** » Tue Dec 29, 2009 8:00 pm

Six year bump...

I was giving someone some guidance on this today and figured I would update this thread for references sake. The mistake I made on this install is that I didn't realize that the stock midpipe on the legacy turbo is a true 2.5" pipe and bigger than a stock WRX midpipe. On subsequent installs I have kept the stock midpipe, along with it's cat pipe and gone with a catless WRX downpipe (like a Cobb). Then I just have the midpipe flange removed, and the piping extended to bolt up to the WRX DP and it's done. Way cleaner and higher performance than my original version of this...

ericem · Post by **ericem** » Tue Dec 29, 2009 8:43 pm

The stock midpipe is 2.25" and the wrx exhaust is 2.5". Unless I measured it wrong?!

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A forum for 89-94 BC-BF(BJ) Legacy Owners and Fans

My turbo back story...I installed one today.

My turbo back story...I installed one today.