My plan is to run a 2.7, 60lb, heat exchanger, and a full exhaust. Would i benefit more from a custom full 3.0" exhaust or a full 2.5" exhaust? I do not want to lose torque due to no backpressure but i am not sure if the 2.5 is big enough to let the blower breath.

 

they say the 2.5 is big enough , you only need a full 3.0 if your pushing over 300 so if u jhave the twinscrew of the turbo thats what i have heard

 

2.5" is PLENTY BIG ENOUGH!

 

2.5" will be fine

 

Check out the search button. Jcm already did all the flow calculations for this. He shows which exaust size is best for you.

 

So, according to calculations, if i will be putting down about 270whp, then i will need bigger than a 2.5?

 

Yes. Go with a 2.75" exhaust

 

2.5-2.75 should be a good size to hang out around.