Hi all, my car is a 1991 z28 5.7 350. everything is stock and from what i have read the first thing to improve would be the exhaust. I am looking to buy new headers and upgrade the entire thing to a 3''. I am having trouble finding parts that will fit in order to keep the dual cats. I want to replace everything essentially in order to get the 3'' system set up so i can build up my engine in the near future. I would like to spend only about $1000, not including labor is this a realistic amount? if so, What parts would work the best ?

My 2 cents: I have a '88 GTA so I don't have to deal with the dual cats but from what I can see Hooker offers the excellent 2055 headers for the 1986-1990 and they will only work with a single 3" cat. The Hooker & Hedman headers shown for the 1991-92's would require a custom Y pipe to include the cats, although I'm sure that this is very doable by a good exhaust fabricator.

It does look like the cat back exhausts are the same for single and dual cat systems for the 1988-1992's because they have the same part number (at least for the Magnaflow systems). My guess is developing and tooling a y-pipe to handle dual cats for the headers is too expensive.

It may not be legal to do away with the dual cats and replace it with a single one but I'm betting that the emission levels would still be within legal limits.

From what I've learned on this site and others is that the Random Technologies high flow single cat will work quite well for HP applications. They show a single 3" cat part #191-30001 and for dual cat applications part number 180-22000

If I keep my stock manifolds I may actually switch to the dual cat system. Magnaflow makes what looks like a high flowing system with mandrel bent stainless Y pipes.

Hope this information was helpful. Good Luck,
Greg

Dyno Don headers, Magnaflow catback and then your golden.