TRUST a catback exhaust system. Basically for a turbo car, what we
need is heaps and heaps of AIR.
and of course with more air in from Cold Air Intake , a large enuff
piping and exhaust will help release the air when turbo boost, thus
pushing the car forward.
another reason why all these exhaust are legal for evo, rex etc....

Can check out BMS, BKS, those are some pretty workshops for
rexes.