I'm planning on taking the rotor housing off of the M90 for cleaning and some mild porting since it'* off of the engine right now. Are there any seals that I'll need to replace while doing this?

You will need a tube of GM red gasket maker to seal the charger back together. Otherwise..you may also want to change the beraring in the back of the casing while you are at it. All stuff is linked on Wrens site about SC'*.. Most likely in the porting/cleaning phase you will get stuff in the needle bearings and need to replace them.

Absolutely change the needle bearings after porting, or any time you're in there. It'* cheap, easy, and good preventive maintenance.

http://www.williamwren.com/superchargers

The information you need is mostly there.

Thanks.