Not sure yet, probably aiming for around 10-12psi... The efficiency of the charger drops off significantly once you pass 12psi to the point where you have temp issues.
In my case, my objectives are a little different to most. When most people say "Oh it goes hard all day" they mean it'll do a few laps in a row, then a couple of cool down laps, then pit till the next session (EG 40 minute break). When i say i i need a car that goes all day, i literally mean 2 * 3+ hour stints going flat out (no cool down laps) only coming in for an occasional pitstop for driver change and refueling. This level of endurance is far more stressful on a car than 1/4 mile drags or one lap sprints.
The other thing is although you can make more power than a V8 supercar, ive yet to see any commodore come close in terms of lap speed, corner speed, top speed or braking performance. A V8 supercar is an amazing machine which most people dont give enough credit for (as it looks like a commodore which of course means its only as good as a taxi).