Bass Junky is not running a GT30, he has a GCG hi-flow with a VG30 ext housing.
I am also running the same turbo, with Tomei Poncams (256 duration[r33]) and head porting. Car made 270rwkw@15psi, on a new dyno dynamics dyno, tunning mode. Externally engine looks stock, apart from fuel reg (but that's also hard to spot).
My engine also started to ping higher in the rev range, this was solved by pulling timing out in that effected area only.
Mafia have you considered cams or even a descent head porting? This will definately release the true potential of the turbo. Honestly, with the fuel, i think that your car is not too bad, but when you have your mind set on a figure i guess you will feel disappointed.
All the best
Al