What size pipes

[95TealCamaro]

I am planning on getting an 80 Seires Flowmaster. Should I run 3" or 2.5" from the cat back to the muffler? What do you think and why. Also should I get a new cat? If so which kind?

[RacerJ]

3" vs. 2.5" is entirely up to you. It's a very debated question. Personally I'm running 2.5", but many people say that 3" sounds better than 2.5", the rub being that there is debate over whether or not you loose low end torque by going to the 3".

Either way. If you want a high flow cat, go over to summit.com and you can pick up a Catco universal high flow for about $50.

[Liquid Silver]

Racer J's right. It's a very debated topic and some people live for their 2.5" pipes, and others swear by their 3" ones. From what I can gather... the 3" peak gain is at a higher RPM than the 2.5" (makes sense since more exhaust is being pushed out at high RPMs). Basically, what I'm trying to say is each muffler gives you a gain in power, but they perform the best at different RPM's. The 2.5" is a little sooner than the 3" (but I recommend you plan on installing at least 3.42's with the 3" exhaust cuz off the line acceleration will be sacrificed a bit). My best friend's running a 3" dynomax on his TBI car... got him $200 for racing an RX7 and it also put him at a 14.8 in the 1/4 mile (with 3.08 gears and no limited slip/posi... not too shabby if you ask me.)

If you want to know the difference between sound with Flowmaster and Dynomax I can easily tell you since every time I go out with my friends I hear each system on the same type of motor [img]smile.gif[/img]

and here we go:

1989 Formula TBI with Flowmaster A.Thunder Catback: very aggressive and a lot of midrange in tone.

1989 Trans Am TBI with Dynomax S.Turbo Catback:
a lot lower in tone than the flowmaster... think of this as a very Bass filled exhaust. (almost sounds like a subwoofer at idle).

One more thing: Dynomax catback is cheaper than Flowmaster's catback... but the flowmaster came with SWEET TIPS... PERFECT Beautiful looking 2.5" chrome slash cuts come with that system... you have to buy tips for a Dynomax (at least this is from my experience).

Hope this helps...

[ March 14, 2002: Message edited by: Liquid Silver ]</p>

[shortdog273]

Get a 2.75" off a z28 or TA like I did

[Camaro15]

what is the part number for the intermediate pipe from summit???

[Ted]

If I were you i'd say **** the backpressure and get 3" pipes. I dont' think your going to be too much at a loss. You can make up for it in performance mods later. It all depends if you are for the little extra performance or more for the little extra sound.

Ted

[Patrick Javert]

Look into a true dual exhaust with a cat after each header, then the pipes coming down to 2 2 1/2 in. I-pipes, an x-crossover right before the s-pipes, s-pipes, and straight to your tips. Don't think it'll be too loud.