Downpipe Size

[GNVYUS 1]

Board member doing mid 9's did a swap between 3" and 3.5" and there was no difference really, it came down to NEEDING the test pipe dump to be open and the 3" will do the job.

But the 3.5" sure does catch the eye. :biggrin:

 

[grocerygetter]

I'd say 3" downpipe and TA headers in SS for the win.

 

[KevinB]

I'd say 3" downpipe and TA headers in SS for the win.

That's what I run and it seems to work pretty good.

 

[Alky V6]

Rule of thumb we use for proper downpipe size. Turbine exducer X 1.25. That will give you typically what the turbine wheel needs for proper flow. That is based on a full catback.

For wastegates....typically external has better flow, control and allows you the use of better flowing housings.

Con is added price and space need for the gate and dump area or pipe routing back into the exhaust system.

Good info. Thanks.