Serious answer
Pure Boost,
Most people running a serious stage 2 set up are not that
worried about exhaust systems. Most pure race cars have
down pipes only and some include a race type staight through
muffler design. The straightline units are wonderful. If you
are running a single turbo street type car then you have a couple options. I think you can purchase a 3.5 inch single system
from Terry Houston or you can have a custom one built. Brian
Burnside in NO Cali runs a stage 2 wet sump with a pt-88.
He built his own system. Not sure if it is 4 inch or 3 1/2.
I hope this helps a little.
BTW my car will have a 4 inch DP with a straight through muffler in it.