But not prohibitive? I know sometimes it's worthless to guess, but at ballpark 200whp is it just a stupid idea? (bragging rights:gay: )¿

Wideopentuning's post indicates that it's basically worth it at any level.
I plan to do 3" but my motivation is suspect. After screwing around so much with my entire build, I just want to do one thing right and not have to think about the "redesign." Feel me?

white90na, thanks for the writeup.


EDIT: Wideopen, I plan to cut the Megan D/P after the last bend, as it straightens to the back of the car, then weld a flange. My "catback" would start there with a 2.5 to 3.0 gradual cone expander and be 3" the rest of the way. Do you see any restriction in the first couple of feet or so of 2.5? I noticed your example used a 3"turboback to achieve those numbers.

I'm somewhat familiar with exhaust gasses cooling/expanding as they flow along the pipe. Hopefully I've answered my own question here.

I guess I'm confused...is what prohibitive? Does the difficulty of routing the 3" exhaust make that option prohibitive? Certainly not; plenty of people have done it. You'd just have to be a better welder/fabricator than me :)

Since there's no performance reason to not go with the largest possible exhaust on the turbo car, and you have the time, money and skill, why not go the 3" route?

BEGi makes their downpipes from 2.5" to 2.75" at the flange.

Ah, my bad. Yes, that's what I was asking. It all sounds good until that end part! I have one semester of MIG under my belt, thanks for the confidence! :noes: :fawk: :ugh:

Agreed my friend.

Ah, sweetness, I think it will work just fine (i just don't know until I'm under the car - as usual). I've also thought about running just a cat, no muffler. Think the noise suppression would be sufficient for my tastes.

Also, I forgot duh I have a 3" high-flow cat and a 3" Ultra-Flo (Dynomax I think) muffler from my other car, so testing is free. :)

whatever. go 3". it works great on my SIX PSI <200 rwhp car!

Trust me...if I can weld (well, sorta...), anyone can.

U of A. Sounds like you have a decent plan. It can be tough on a Miata to get away with a 3" downpipe with a high mounted turbo.

yeah, the welder cut into the chassis on mine. there's pics on my garage thing. It will not be a bottleneck till 600hp though!