If you already have a turboback exhaust, you can purchase the AP and flash your vehicle to stage 2. The uppipe is not required for stage 2, but it sure isn't a bad idea. You will notice your turbo spooling up a bit quicker.
As far as the suspension goes, there's a few things you can do. Front and rear sway bars and end links are a good way to go. If you don't mind putting springs on, that helps out a bit(again, depends on how far you want to go). But the sway bars and end links are a good way to go. Also, what kind of tires do you run? That's a good mod too. Hopefully you folks don't have the RE-92's that we got stuck with.
Hope that helps.