How much Hp can a single 3.5" exhaust pipe support? If it matters I am running a 4" down pipe into it.

 

A single 3.5 down pipe and exhaust can go into 4 digit power levels.. So it will support enough for most street set ups..

 

I found this: http://www.exhaustvideos.com/faq/how-to-calculate-muffler-size-pipe-diameter/

But it looks for na vehicles

Turbo is a different cookie

 

That's what I thought. Thanks.

 

Not enough information really. Depends on the length of pipe, number of turns, and muffler(s). The turbo will always be the bottle neck for power, not the downpipe. To ensure no additional losses post turbo 120% of the turbo's exducer on the exh size is the "rule of thumb". So 75mm an under are fine with 3.5"... anything larger and I'd bump up the downpipe and exhaust to match...

 

yeah i made 750 hp with a single 3 inch pipe into a t6

 

You CAN make 1500hp on a 3" pipe... But would it have made more power with a larger pipe is the question...