Ok, recently my intermediate pipe broke where it meets the cat. So i need to order a new cat because i found out some one gutted mine out(no wonder i failed emissions) and need a new intermediate pipe. Here is the thing. on the inlet side of the cat it looks like it is 2.5 inches and on the outlet side it is 3 inches(i measured, the cat )and where the intermediate pipe goes into the muffler it is 3 inches, now are these the right pipe sizes for the stock exhaust, i thought my exhaust was supposed to be 2.25 all the way back. I need some info, right now my exhaust setup is manifolds to y-pipe to gutted cat, that's it and it is so darn loud it is killing my ears, some one please help. Thanks in advance

 

Why don't you just keep everything 3" to make it easier?

 

Sounds to me like someone changed the exhaust.

Gutted cat and 3" muffler inlet.
Don't sound stock to me.

Look at your muffler and if it don't say GM then it's aftermarket.

I agree with the previous post.
Stick with a 3" system, I've got a stock exhaust on mine right now and have a new cat and muffler and just waiting for the funds for a 3" intermediate pipe and some headers & y-pipe.

If you plan on doing any future mods to the engine you'll have wished that you'd gone with the 3" system.

Also,
It will be much cheaper to just get a new cat and intermediate pipe than a whole new exhaust system.

 

I want to keep the 3inch stuff but I can't find it. Summit says they don't sell a 3inch cat for my car nor do they have the 3inch Intermediate pipe. The cat has AC stamped on it, and i assume it means it is ac delco, not sure. If it is does anyone know where i can pick it up and where can i get the Intermediate pipe. I called a couple of parts places today and they said they don't have a 3inch cat that will bolt on to my car. The parts that are on there now bolt right in the inlet part of the cat is a clamp and the outlet part has that oval piece that presses the I pipe against the cat when you put the 2 bolts in. I need these parts immediately, i think my hearing is starting to be affected by it. Plus i don't need any stupid tickets, i have enough problems as it is. Any help would be greatly appreciated. Oh btw, do Hooker Headers come with a y pipe and would it fit the 3inch cat that is on my car now or is it 2.25. thanks.

 

I think you can have an exhaust shop make you the i pipe, and just buy a 16 inch long 3inch universal cat with one air tubing inlet. Measure your cat to make sure that is correct, though.

Not sure about hooker headers, try a summit catalog.

 

I was looking in the year one catalog today and they have a 3inch inlet/outlet random tech cat for my car and the 3inch I pipe so i am wondering if this was possibly some kind of option, OR does someone else make these parts, i mean year one wants 300 dollars just for the cat . I can get an exhaust system for that. Someone has to have the answers I seek. I am not going to pay 500 for just a cat and an I pipe, just won't happen, not today, not tomorrow, not EVER. So whoever is the exhaust MASTER out there please help. I appreciate it.

 

Call your local muffler shops.

I checked a few muffler shops myself a few months back looking for a 3" I-pipe and they had it in stock and was under $140 + install.

I've never seen or heard of a cat that goes from 2.5" in to 3" out.

When ordering parts for your car you need to tell them what you want vs what year/make the car is.

Jegs has a 3" in/out cat and is part # 289-15143 $129.95.

Sounds to me like you have a 2.5" in/out cat and a 3" exhaust system.
Which is common and would be flowmaster cat back exhaust part # 17233. Which is a 3" exhaust that mounts to a 2.5" cat. This is just one example there are plenty of other exhaust systems on the market with the same features.

I just bought a catco cat and it's a 2.5" in and out. But that depends on where you measure it also.
On the exit side that hooks up to the I-pipe there is a bump and it could easily measure 3".
I think this is the cat that would hook up to a 3" I-pipe allowing you to keep a stock y-pipe.

Then theres the real 3" cat which would require a 3" y-pipe.

As for the headers.....

I believe all hooker headers come with a 3" collector.
some of their headers come with a y-pipe, and others you need to order the y-pipe. Depends on which model your looking at.

 

The stock cat is 3" on the outlet side I dont remember if its 2.5 on the inlet side though. I can't help you on the stock muffler inlet size becasue I have never had a stock muffler on my car.

------------------

1987 Iroc 350
GTS headlight/tail light covers
Camaro SS Wheels w/Sumitomo HTR ZII 275 rear, 255's in front
K&N filters
Adjustable Borla cat back
SLP 1 3/4 headers
w/ Air born coating
3" Catco cat
Large tube runners
ported plenum
Holley afpr

FUTURE GOAL:
To go really F'in fast!!!

Some pics of it at
http://albums.photopoint.com/j/Album...949&Auth=false or (still working on) http://members.cardomain.com/john87iroc