My car has the following spec turbo from CR Turbos (a TSF02) although I hear Wilky is the man to see for a turbo:

2WD Cosworth compressor housing
55 AR compressor wheel
360 degree ball bearing
-31 actuator.

At least on my engine and the road it actually makes the engine a lovely setup, far more usable than my last car if I am honest (a 944 Turbo with the larger turbo from the factory; that was very flat until over 3,000RPM where the turbo literally came in with some force and as if it was on a switch!).

That last note is pretty important. Bigger is not always better and the turbo in all honesty should be chosen for what you want to achieve from the car (i.e a nicer road machine or more of a screamer at the expense of drivability). Pub bragging rights are all good and well I admit but they are just that .