I know that with a 3" exhaust the spool time on a turbo will be at a lower rpm but does it also give you better torque at the same psi as a 2.5" exhaust would? I know this is a noob question but I would like to know if I should go through the hassle of having a 3" custom made or if I should just buy a 2.5 catback and put it on myself.

 

for a turbo set up a 3" setup if you are going for higher numbers. like over 350+ IMO

i'de stay with 2.5" if its a basic turbo kit.

as for the torque, i wouldnt worry about it the turbo is going to make up for the difference.

 

I'm going for 200whp at first then maybe down the line somewhere try for 250 with new rods and pistons.