Custom stainless 2.5" system dual cats
Thread Starter
Joined: Jun 2000
Posts: 5,364
Likes: 51
From: Enschede, Netherlands
Car: 82 TA 87 IZ L98 88 IZ LB9 88 IZ L98
Engine: 5.7TBI 5,7TPI 5.0TPI, 5,7TPI
Transmission: T5, 700R4, T5, 700R4
Axle/Gears: 3.08, 3.27, 3.45, 3.27
Custom stainless 2.5" system dual cats
Built this for my buddies 92 Procharged GTA. He has the Edelbrock headers and they are rather small with only 2.5" collectors so no way to run 3" into 2.75 like I have. Being a 92 and requiring emissions testing I had to install a cat con. I opted for 2 high flow ones because of the supercharger. Built a custom merge section that runs into the rear section of the 3" setup that he already had.
Here's some pics
Cat con w/ merge and bung for wideband setup (tuning)

Mounted so that it's under the heat shield w/ access to the O2 sensor bung. Used the stock exhaust hanger

Starting off the header, a real tight fit. Had to flatten the tube into a funky shape to clear the crossmember and oil pan. Especially the bend around the pan right off the headers was a tricky one to get tight & right

Some more pipework done

Gotta clear the modified UMI SFC too

Here's some pics

Cat con w/ merge and bung for wideband setup (tuning)

Mounted so that it's under the heat shield w/ access to the O2 sensor bung. Used the stock exhaust hanger

Starting off the header, a real tight fit. Had to flatten the tube into a funky shape to clear the crossmember and oil pan. Especially the bend around the pan right off the headers was a tricky one to get tight & right

Some more pipework done

Gotta clear the modified UMI SFC too

Thread Starter
Joined: Jun 2000
Posts: 5,364
Likes: 51
From: Enschede, Netherlands
Car: 82 TA 87 IZ L98 88 IZ LB9 88 IZ L98
Engine: 5.7TBI 5,7TPI 5.0TPI, 5,7TPI
Transmission: T5, 700R4, T5, 700R4
Axle/Gears: 3.08, 3.27, 3.45, 3.27
Re: Custom stainless 2.5" system dual cats
Ended up with this, the "crack" in the shorter pipe still has to be welded up, that part still needs a little tweaking. I used 2.5" V bands to be able to remove the 2 forward pipes one at a time. If I were to weld them together like a Y pipe I could never reinstall them around the kickout sump


All in all, pretty neat if I say so myself...and yes, I'm a cheap bastard, I don't use backing gas


All in all, pretty neat if I say so myself...and yes, I'm a cheap bastard, I don't use backing gas
Supreme Member
Joined: Feb 2010
Posts: 1,446
Likes: 2
From: Orlando
Car: 1991 Camaro Z28
Engine: 357, Canfield heads, solid roller,
Transmission: Upgraded 03 Cobra T56
Axle/Gears: 9" 3.50 gears and Detroit Locker
Re: Custom stainless 2.5" system dual cats
Looks very good. BTW, what is backing gas?
Thread Starter
Joined: Jun 2000
Posts: 5,364
Likes: 51
From: Enschede, Netherlands
Car: 82 TA 87 IZ L98 88 IZ LB9 88 IZ L98
Engine: 5.7TBI 5,7TPI 5.0TPI, 5,7TPI
Transmission: T5, 700R4, T5, 700R4
Axle/Gears: 3.08, 3.27, 3.45, 3.27
Re: Custom stainless 2.5" system dual cats
Argon on the inside of the pipe, this way the weld when fully penetrating doesn't oxidize on the back and turns the weld gray. It you'd look on the inside you'd see the welds having a rough consistency on the inside commonly known as sugaring. Backing gas will consume argon so much faster than welding without it and I'm running through gas like crazy. A 10 Liter cylinder is a whopping $60 here.
This is what the inside would look like

With backing gas you'd get all those pretty rainbow colors... oh well LOL
This is what the inside would look like

With backing gas you'd get all those pretty rainbow colors... oh well LOL
Thread Starter
Joined: Jun 2000
Posts: 5,364
Likes: 51
From: Enschede, Netherlands
Car: 82 TA 87 IZ L98 88 IZ LB9 88 IZ L98
Engine: 5.7TBI 5,7TPI 5.0TPI, 5,7TPI
Transmission: T5, 700R4, T5, 700R4
Axle/Gears: 3.08, 3.27, 3.45, 3.27
Re: Custom stainless 2.5" system dual cats
All done:
Trending Topics
Thread Starter
Joined: Jun 2000
Posts: 5,364
Likes: 51
From: Enschede, Netherlands
Car: 82 TA 87 IZ L98 88 IZ LB9 88 IZ L98
Engine: 5.7TBI 5,7TPI 5.0TPI, 5,7TPI
Transmission: T5, 700R4, T5, 700R4
Axle/Gears: 3.08, 3.27, 3.45, 3.27
Re: Custom stainless 2.5" system dual cats
Here's a vid of how it sounds, still running a tad rich and taking it easy as it's a fresh build, still needs tuning. Sounds much better than before.
http://www.youtube.com/watch?v=LOL8g_tx3ts
http://www.youtube.com/watch?v=LOL8g_tx3ts
Joined: May 2005
Posts: 972
Likes: 11
From: Winnipeg, Manitoba. Canada
Car: 1989 T-Top GTA
Engine: 5.7L TPI> 6.2L
Transmission: 700R-4
Axle/Gears: 3.27
Re: Custom stainless 2.5" system dual cats
Very Nice Work!!!
Sounds great too!!!
I'm gonna have a ramp lift like that one day!!!
Sounds great too!!!
I'm gonna have a ramp lift like that one day!!!
Supreme Member
Joined: Aug 2001
Posts: 1,337
Likes: 26
From: Wesley Chapel, Florida
Car: 1991 Camaro Z28
Engine: Dart SHP 406ci T88 turbo
Transmission: T56
Axle/Gears: QP 35 spline Ford 9" 3.50 gears
Re: Custom stainless 2.5" system dual cats
Awesome work. I made my own true dual exhaust 2.5" but my ypipe is 2.25" from the headers up to just before the x-pipe because there's not much room to do 2.5" due to lack oil pan clearance. Is your y-pipe 2.5"? Did you have any problems with clearance?
Thread Starter
Joined: Jun 2000
Posts: 5,364
Likes: 51
From: Enschede, Netherlands
Car: 82 TA 87 IZ L98 88 IZ LB9 88 IZ L98
Engine: 5.7TBI 5,7TPI 5.0TPI, 5,7TPI
Transmission: T5, 700R4, T5, 700R4
Axle/Gears: 3.08, 3.27, 3.45, 3.27
Re: Custom stainless 2.5" system dual cats
On a stock pan you can go larger, I have a 3" into 2.75" and then 2.75 all the way on my 87. The 3" is only the first couple of inches after the V band, if you look carefully you can see it necks down quickly after.

I agree the car looks awesome, unfortunately it isn't mine. It's 69Cyclones.
Supreme Member
Joined: Aug 2001
Posts: 1,337
Likes: 26
From: Wesley Chapel, Florida
Car: 1991 Camaro Z28
Engine: Dart SHP 406ci T88 turbo
Transmission: T56
Axle/Gears: QP 35 spline Ford 9" 3.50 gears
Re: Custom stainless 2.5" system dual cats
I'm getting a BMR kmember and in a few months so I believe that should give me the extra clearance I need to run 2.5" ypipes and this oil pan http://www.jegs.com/i/JEGS/555/50223/10002/-1
Thread Starter
Joined: Jun 2000
Posts: 5,364
Likes: 51
From: Enschede, Netherlands
Car: 82 TA 87 IZ L98 88 IZ LB9 88 IZ L98
Engine: 5.7TBI 5,7TPI 5.0TPI, 5,7TPI
Transmission: T5, 700R4, T5, 700R4
Axle/Gears: 3.08, 3.27, 3.45, 3.27
Re: Custom stainless 2.5" system dual cats
Those pans are a bitch to get pipes aroud, just like on the gTA. Just look at the weird angle coming off the drivers side header. Surely some ponies are lost there. In hindsight i shouold have cut off part of the collector, used a big elbow and then a V band clamp like on mine to improve the angle there. The canton pan is such a better fit but it's pricey.
Supreme Member
Joined: Aug 2001
Posts: 1,337
Likes: 26
From: Wesley Chapel, Florida
Car: 1991 Camaro Z28
Engine: Dart SHP 406ci T88 turbo
Transmission: T56
Axle/Gears: QP 35 spline Ford 9" 3.50 gears
Re: Custom stainless 2.5" system dual cats
The little turn you did there off the header still looks pretty good to me. I may have to perform surgery on the Jegs pan by sectioning off an inch from the front part of the sump. But then again I may not have to. I'll deal with it once I get all the parts in.
Supreme Member
Joined: Jan 2009
Posts: 1,126
Likes: 0
From: Columbus Ohio
Car: 91 Z28,64ImpalaSS4094spd,67 Galaxy
Engine: Dart 415Profiler hd,cmprlrs,Hlly750
Transmission: Built 700R4, 3200 stall
Axle/Gears: 3:89 Moser 9"
Re: Custom stainless 2.5" system dual cats
Twin, very nice work, very nice....
Thread Starter
Joined: Jun 2000
Posts: 5,364
Likes: 51
From: Enschede, Netherlands
Car: 82 TA 87 IZ L98 88 IZ LB9 88 IZ L98
Engine: 5.7TBI 5,7TPI 5.0TPI, 5,7TPI
Transmission: T5, 700R4, T5, 700R4
Axle/Gears: 3.08, 3.27, 3.45, 3.27
Re: Custom stainless 2.5" system dual cats
Thanks 
Stainless exhaust systems is what I like to do
Here's some other stuff I put together, a 67 barracua,

70 coronet boom tubes

Work in progress, side dump exhaust for 80 formula turbo

82 corvette 2.75" true duals

Stainless exhaust systems is what I like to do
Here's some other stuff I put together, a 67 barracua,
70 coronet boom tubes

Work in progress, side dump exhaust for 80 formula turbo

82 corvette 2.75" true duals
Senior Member
Joined: May 2005
Posts: 777
Likes: 1
From: Windsor Ontario Canada
Car: 89 jaguar xjs convertable
Engine: 89 L98 5.7 TPI
Transmission: 700R4
Axle/Gears: 3.23 dana 44
Re: Custom stainless 2.5" system dual cats
Man that d/s header really phucked you hey? Personally I would have sectioned the front crossmember to give myself more room between it and the pan. You really did a nice job considering what you had to work with!
Rob Wade aka "Mufflerguy"
Custom exhaust/header fab
See more of my work at
http://s268.photobucket.com/albums/jj24/mufflrguy/
Rob Wade aka "Mufflerguy"
Custom exhaust/header fab
See more of my work at
http://s268.photobucket.com/albums/jj24/mufflrguy/
Last edited by Rob Wade; Aug 2, 2010 at 02:26 PM.
Thread Starter
Joined: Jun 2000
Posts: 5,364
Likes: 51
From: Enschede, Netherlands
Car: 82 TA 87 IZ L98 88 IZ LB9 88 IZ L98
Engine: 5.7TBI 5,7TPI 5.0TPI, 5,7TPI
Transmission: T5, 700R4, T5, 700R4
Axle/Gears: 3.08, 3.27, 3.45, 3.27
Re: Custom stainless 2.5" system dual cats
the problem is not so much the crossmember, it's the oil pan. The header aims straight into it. Save a hundred on a pan and then having to go through this LOL
i looked through your photobucket
nice!!!
i looked through your photobucket
nice!!! Thread
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