I want to install an 05 catback on an 04 has anyone tried it yet? I already have the 05 rear bumper but I want to put a new exhaust on it to match. Any help will be great.

 

Some exhaust hangers might be in the wrong location, but lots of 04 guys convert.

 

i also believe the 05 and 06 cars have different size pipes. it would be a sweet mod non the less. good luck with it. there are a ton of threads about this swap on ls1gto.com.

 

The midpipes on the '04s are different. I'm not positive about the manifolds. If the manifolds are the same, you'll have to get a set of stock midpipes from an '05/'06 in order to get the catback to bolt up. Now if you have headers, just get the '05+ mid pipes for the particular brand of header you're running, and you'll be all set.

 

Think you need the 05/06 midpipes to replace your 04 midpipes (04 is 2.25" compared to 05/06 2.5").

You'll also need to weld in or somehow make a hangar for the rear passenger side tailpipe.

Of course you'll need the 05/06 rear bumper or cut the 04 bumper.

Here are a couple of links from the LS1GTO forum.

http://www.ls1gto.com/forums/showthread.php?t=115776

http://www.ls1gto.com/forums/showthread.php?t=127039

 

I have done it, and am in the process of selling bolt in passenger side hangers for this swap. FYI, if not doing headers. Just install a set of 05' converter pipes.

Let me know if you need anything at all.

 

+1 I think the 05/05 are 2.5" while the 04 are 2.25". I first got the Borla split dual exhaust which was 2.25" and later I got a custom 3" system with Magnaflows and X-Pipe. At some point I am thinking of doing away with the muffler mount forward of the IRS in favor of an 05 style setup. Spintechs work nice because they are light and small.

 

Or you can just take it to an exhaust shop and fab up from the axle back and install a hanger.