I have a project in the works, being a turbo GSR EF Hatchback. The turbo I'm using is a T04B 60-1, .70 a/r and I'm actually looking for some pretty big numbers on the stock bottom end once it rolls out.

The turbo is quite large, could be called a T4 turbo I suppose, so would there be any benefit to running a 4 in. downpipe as opposed to a 3 in. downpipe? I didn't know if it would be over the top or not, and I figure someone would know better than I would.

Also, for tuning, is there any program preffered for the EF itself? I can't decide on either Hondata or the AEM EMS, but I'm not sure if I want to spend all the dough on the EMS. Someone enlighten me!