Well you will have to find a way to pull some timing in addition to the fuel, IE crane or MSD ignition, or greddy e-manage. For the 8 injector setup you have to buy a new regulator for the fuel system. Not only that but you really have to tune this 8 injector setup, it's not plug and play. Now I will say this, if you don't feel you are ready to rebuild, and don't know the basics of a turbo 420a, 12psi on stock internals is probally not for you,.....yet. You need to stick with the basics for now. Go with stage 1 or 2 until you learn everything you need to know, then think about turning it up. It's going to take a lot of tuning to push the envelope like that, and it will have to be DEAD ON. IMO, just from what you have said here, you are not ready for that. Slow down a bit and go in stages, because if you try to go 12 psi on stock internals at your current level of knowldge, your going to blow it up.

I edited to the wiki!