The entire SC package was designed around a very small and innefficient supercharger. It sucks for us, but all the parts that support the M90 are sized to match it perfectly (TB, MAF, IC, etc). With proper tuning and a good supercharger (ie. more boost) these cars will make 150 more HP than stock. However, because the supercharger is the problem, it is not an inexpensive solution. Just replacing the supercharger with a more efficient source of boost will result in more power gains than all other modifications combined.
So in a word, yes more boost will make more power. Problem is the M90 supercharger is not an efficient source for the necessary boost.