How much of the gain of a aftermarket catback is due to the muffler? Stock I-pipe is 2.75'', and most catbacks are 3'', right? Can't imagine a big gain by opening it up from .25'' I could be wrong about that.

I'm putting pacesetter LT's on my car, and my I-pipe is stock with a Flowmaster muffler/hi-flow cats. I want to take advantage of the flow from the headers, but I love the sound of the Flowmaster. I also don't have the $$$ right now for a catback.

I'm not planning on going beyond bolt-on mods, as this car needs to be a daily driver. If I get to 300rwhp I'll be content for this car.

If I'm only going to gain 5hp with new catback, I won't do it. I'll just keep my Flowmaster on, I do like the sound(I know some don't, but..)

I remember seeing this mentioned on here somewhere, but couldn't find it...

 

if you plan on using long tubes and reaching 300 rwhp, a catback is necessary. the stock pipe may be alright, but it doesn't help the longtubes breathe. the flowmaster doesn't get much of a rep around here. the stock piping is not mandrel bent, and the muffler inlet holes and oulet holes are not the same size as they are in the catback system. you might want opt for a better system than a flowmaster....

 

Well the stock 2.75" tubing is good for 310 hp with zero loss if you have a different muffler because the muffler is the real restriction.

 

I make 420hp at the crank with a stock I pipe. Wonder what kind of gains I would see by just switching to a bigger pipe...

 

Well here's some very good exhaust info provided by OldSchoolSS.
http://web.camaross.com/forums/showt...d+exhaust+info

 

Im no expert on exhaust but i'd say you would probably gain 15-20 hp.

 

I've heard mostly negative things about the flowmaster catback-how it is restrictive and all. I thought the actual muffler(by itself) was OK. I would not get a flowmaster catback if I were to do the whole thing.

My thought was that the stock muffler was the most restrictive point of the stock catback system. I'm just trying to rationalize not spending any more cash right now .

If eliminating the stock muffler gets me most of the way there, I can live with it for now.

 

Save yourself $300-$600 and get yourself a cutout. It'll provide more power than any cat=back.

Or save yourself of the $30 a cutout costs, and just cut off the cat-back. Then you'll drop 50 pounds off the car too.

 

That's my plan.

 

has anybody tried adding 2 glasspacks side by side with turndowns or out the pass side together at the end of the stock y, on a 97 firebird ,

 

A cutout is in the future for this car, which is even less reason for me to go crazy w/ an expensive catback.

My last car had a two foot pipe for an exhaust system-no muffler whatsoever. It was like that for years. I'm sure I don't want to go back there