For power and drivability, I would recommend the Revhard kit with a better fuel management system. It will net some good gains on a stock motor at low boost and the kit is pretty solid.

For exhaust, I would recommend to get full 3" all the way back. It will allow the quickest spool time with little/no compromise in torque or horsepower. The Thermal 3" Turbo exhaust is a beautiful exhaust. If you don't feel like spending that much on an exhaust, www.kteller.com sells prebent piping, so you could pick out a custom muffler, resonator, cat/straight pipe, and bends for a 3" downpipe and it would be cheaper to do that.