Sound just about right at the moment, and as Spadge correctly states, next thing on your list is a bigger intercooler, and then you can add a bit more boost. Up to about 25psi. But take the advice of some of the Real Tuners...... Karl Norris, Stu (Motorsport Developements) Mark Shead (MAD Developements) etc.

BUT : Remember that it's just not a matter of turning up the boost, without adding extra fuel at the same time. GET IT MAPPED PROPERLY, OTHERWISE YOU'LL PROBABLY MELT SOMETHING, ALL ENDING IN