I'm actually building a single turbo kit with a 6.5 td for my car. The headers are nearly finished and my work progress very well. I'm wondering what downpipe size i should use? I installed a 3" downpipe on my friends stock 87 supra and this mods add tons off low end torque ( faster spool up). His car is a 3 liter so should i put a bigger downpipe? 3" or 3.5"? I saw a few mustangs with 3" downpipe on single turbo kit. It will not cost me a lot more to built a 3.5" and i've heard that you can't go to big with a downpipe. Is it true?

 

You heard what everyone else is hearing. Go as big as you can fit in there.

 

I can't find 3.5" to to 2.5" Y-pipe( i want to retain the dual exhaust) But i found a 3" to 2.5" Y-pipe. I will use my mac longtube H-pipe. Where can i find a 3.5" to 2.5 Y-pipe? Or will the 3" downpipe be O.K.? I just read on another thread that a 3" downpipe will support 800hp. I will be happy if i have 400 rwhp. Thanks!

 

So run a 3" dual exhaust, and split from 3.5" to dual 3"...will probably be a custom Y-pipe but it's very doable.

 

I want to retain the dual exhaust because i think that a single 3.5" single would maybe look ugly. A single exhaust would be easier to build but i'm afraid of the result. Anyone have done this?

 

just dump it before the axle, nobody will ever know the difference except that there won't be any tailpipes

 

Too bad dumps are illegal in some spots.

 

ahh...details details

 

I have a gt so even if i fabricate a ugly tailpipe, nobody could see it

 

Make sure to run Straight through type mufflers. Any Chamberd type mufflers will slowdown the exhaust gas. I just bought a Dynomax 3.5 Ultra Flow muffler (Over priced Glasspack) 75$

 

I actualy have magnaflow's on my car and will never put anything else.

 

Yea... go with a 3.5"

I have a V6 Mustang, and have a 3.5" downpipe, coming out of my single turbo. Mine is dumping into the fender, with no muffler