I was wondering about the actual gains of a cat-back system if the rest of the exhaust is already aftermarket, mac mids, mac ORY-pipe, no cats into---->stock cat-back. There are posts everywhere about the minimal gains of a cat-back on a stock car, not repeating that, just wondering would the gains be more or less if the rest of the exhaust is already aftermarket.....would be nice to keep the stock apperance, wink wink.

 

i put a corsa on my car and gained pretty much what they claimed on their site...it was prett much stock with headers and a y-pipe...still had 2 cats on it too.

 

From what I recall, people were picking up about 9-11rwhp and 7-8RWTQ from cat backs on stock cars, with headers probaly a little more but nothing dramatic, probably be about that.

 

It will help even more with a CAI..

 

I wonder, heres the deal, I'll have the mac 94-95 headers/ory-pipe/into stock catback now. But if I were to get a diff cat-back, I'd probably have to stick something in the cat spot, for noise reduction, since it would be just a little to loud probably. What I'm wondering is if stock restriction(of mac+ory+stock catback) is greater than the restricition of a aftermarket cat-back plus like a bullet or something.....since the stocker is a little more quiet???

 

If your just wanting to keep your stock apperance, then do the obvious and have your stock tips welded on to the ends of the tailpipes. As far as stock sounding, im sure its louder than it was stock now.

 

I don't know actual HP gains, but I do have a similar setup. 95 Formula, Mac Headers, Mac y-pipe (regular, not off-road) and the single cat (stock location, hollowed) and I had a stock exhaust up until last week. I put a Hooker catback on it and the sound improvement was amazing! Sounds real mean over 2500 rpm's. At idle, it's just a little louder then stock. I did feel a SOTP difference, but have not had dyno's or run at the track......yet. I also added an SLP CAI just 2 days ago and that gives a "4-barrel" sound when you crack it open. Did notice a little performance with that as well. Wish I had HP #'s for you, but I just wanted to chime in with the install & sound info. As far as apperances, the Hooker came with chrome tips and look VERY similar to the stock pipes. It was like $295 shipped from Summit.
Mike

 

from my moroso CAI/trick flow elbow and my flowmaster when I first got my car I gained 29rwhp, I love my flowmaster!! and now I have alot more power and my exhaust keeps on the ball!!