I modified my gt2860rs by fitting an after market GTX2860 compressor wheel. It has a -48 exhaust housing on the back. It is very responsive, boosts 24psi from around 3100rpm up to 5800rpm when the boost drops off to 19psi till redline 7000rpm. For what it's worth the car was put on the dyno and came back with 327bhp and 325 pounds per foot torque.
It's a very usable car cosworth YB engine.

Tim.