This is a hypothetical question, cause this looks like it could take some work.

Intense sells some forged 9.5:1 pistons with a .010 overbore for L67 engines.

Now, Intense says that the 9.5 pistons should be used for a motor with the stock M90 blower. Since the compression goes up from 8.5 to 9.5, will it be wise to use a smaller pulley on the blower. 3.4? 3.25?

How will this affect the engine?

You'd want a bigger pulley, with less boost, The compression would be higher naturally, and you can't run as much boost? I know you have to lower compression witth turbo'* to compesate for boost.