I'm no expert either but I have rebuilt some engines before and with the experience I have and the feedback I've read over the years ... after market intakes generally are no better than stock iron manifolds. This appears to be isolated to Pontiac engines. So if your brand aftermarket manifold is "awesome" for a Chevy, it's not necessary "awesome" for a Pontiac.

IMO - go stock with the intake, lot's of other things you can do to get more performance and I lot less work.