You'll start to run lean if you're running over 21 psi above 6000 rpm. So a fuel pump is in order. I would also add head studs if you plan to dial it past 22-23 psi. These are pretty inexpensive add-ons. At that point you should be putting out 300 - 330 WHP which is pretty good considering stock is around 240-250 WHP. You could get another 20+ with chip and dyno tune and 20 more with cams and timing gear.
After that you'll need a bigger turbo, the stock turbo would be so far off of the island it'll just be heating up the intake charge.