I'm going back and forth on my exhaust plan and I'm running out of time.
Ls1 with ls6 cam, Turbonetics tc78 in a BMW 528i. I don't plan on running a cut out or a dump at any time. I want a full exhaust, all the way to the back bumper. It won't have a catalytic converter. The down pipe is 3". A single 3" all the way back would be ideal due to a lack of space to run the tail pipe. I also have been considering running 3" past the transmission, then splitting into twin 2.5" pipes. May be possible to go from 3" to 3.5" behind the transmission. I could run an open wastegate to help offset the smaller 3" exhaust if I went that route. Planning to run 8-10 psi at this point and hoping for low 500's at the tire. Down the road I may go for 600, I would love some insite from guys who have done some testing this!

 

Subscribed, curious also how a full exhaust effects a turbo car.

 

I run a full 3 inch with a magna flow muffler and tail pipe. I gained about 25rwhp by opening the cutout from 4500rpm out. This was around 12psi and 587rwhp.

 

That's not terrible, do you have an open wastegate?

 

I plan to dump my wastegate into open air, run 4" dp from the turbo down to 3" through the k member all yhe way back through a magnaflow catback w a cut out just past the trans where it meeta the catback.

 

What car and complwtw setup do you have?

 

Open gate. The car is a fox body. I have about 3' of 3.5" pipe then the rest is all 3". I have a cut out just before the muffler. In my situation I think that my turbine is more of a restriction than the exhaust. I'm running a little mpt70 with a .96ar. I will have some more comparisons with my s475.

 

My exhaust ar is 1.05 so not sure if that effects much.

 

I run 3 inch exhaust with a one chamber flowmaster on a LT1 a long time ago. It did fine . I wouldn't run a flowmaster on a turbo setup anymore but it will work with full exhaust. My corvette has full exhaust it made 670 to the wheels on a stock ls6 on 14 psi.