What car is this on? How are you running 8 psi on that turbo with that exhaust setup? Just to start with, the wastegate spring pressure is higher than 8 psi unless it's been changed somehow (which I guess Greddy could've done, though I didn't know Greddy offered an Evo 16g).

Let us know what kind of car you're dealing with. Taking your post at face value and assuming you have a DSM, at first glance I'd say bigger injectors and about 10 psi more boost in that order.