Im going to be doing a DOD cam swap on my 2005 GXP in the next month or so. I also want to add some hp to the car while i have the engine tore down. So far the list of parts im going to buy includes;

Lifters x16
Lifter guides x4
Head gaskets x2
Head bolt kit x2
Balancer bolt x1
Front water pump cover to block gaskets
modified valley cover
LS6 cam
LS6 intake
pushrods
valve springs

Im open to suggestions on what else I could buy to boost more hp. Im also open to suggestions on a better cam/intake setup. Im not looking for a monster cam setup, just something more mild. Also whats a good header setup, i see doug thorley headers alot. Thanks in advance for any help.