Hi there,
A 4x4 Intercooler is a good mod onto your car, i,m having the exact same set=up as you as we speak by Reyland in Birmingham. I have a Level 6 ecu, 803s, Breather, GRP-A headgasket, -31 Actu 3bar. my car will be peaking@ 23psi holding 17ish, i also have the Turbo Technics Stage 2 T3 with the 360 thrust bearing.
If i were you i,d give Martin a call and get him to check your car over.
What fuel Pump is on the car??