Is a 4" exhaust to big for my power goals?

[QWIKSTRIKE]

on our cars giant exhaust + lowered suspension = disaster.

why don't people go with cut-outs instead of a giant exhaust? my cut out is excellent, and when closed it runs through my 3" setup with cat and muffler to keep noise down for long trips. i'm even thinking of getting a silencer to reduce noise even more or going with an oval tubing setup.

i'd recommend getting that oval tubing, i posted this thread about it:
http://www.supramania.com/forums/showthread.php?t=34842

if i redo my exhaust (so i can get a new cat, muffler and silencer and run cleaner/quieter when the cut-out is closed) i'm going to get the 3-1/2" round equivalent (2-1/2" x 4" oval)

Get it custom produced to mate with the cars underside an coil overs is all you do man.

 

[p5150]

So to answer the original question, I dont think any exhaust is "too big" for your goals. You will see gains that diminish as you get larger and larger. It comes down to the factors you are willing to live with:

1. Cost of materials.
2. Proximity of exhaust system to ground.
3. Difficulty of making a 4" downpipe fit.

Im working on mine right now and trust me man - it is a tight fit. But at least with a 4" you will be set for whatever else comes your way! Ive spent about 500-600 in materials for all of the stainless, flanges, vband clamps, flex joints and polished muffler.

 

[X-man]

thats a big difference with just a catback. is your downpipe a 4"?

Yes, it's a 4 inch v band from the turbo through the convertor "simulator".

Sean

 

[X-man]

I built mine out of big rig IC piping. It's 4 inch mandrel bent pipe and the wall thickness is right in the area with exhaust pipe. I bought the flange from ATP and bothe Dynomax mufflers from Advance Auto.
Costs

4 inch Dynomax round muffler 70.00
4 inch Dynomax bullet muffler "convertor simulator" 35.00
4 inch v-band flange 40.00

building big rigs and having a TIG welder priceless.

I have had this exhaust on two different turbo set ups. My SP67 with an HKS long runner manifold and the header I built with my GT42. I started with a 3 inch v-band flange off my 67 and hand formed the elbow to meet a 4 inch pipe. It left the turbo and immediately expanded to 4 inch through the 90 degree elbow. I did the same thing for Dave B's car but with 3.5" pipe.

Sean