You won't need lower compression pistons for that low boost level, and it will cause you to lose power all around. I'd always try to run the highest safe compression for the amount of boost you're using. If you'll be getting the upgrade (smaller diameter) pulley for higher boost, then you may need a slight bit lower compression, but not much (if at all)...

The lower the compression, the lower the cylinder pressure for the same amount of boost, so the lower the power. This is why low compression, high boost-capable cars are dogs when the turbo isn't spooled, and also the reason why high compression race engines can make great power not using forced induction. SO don't just jump into lowering the compression a bunch when you're only going to be going 10-12 PSI with that supercharger. A lot of your safety margin against detonation is in the tuning, not the low compression.