I wouldn't run it at 11.8, your just asking for trouble on pump. I don't see how someone can tune a car to "stop" making power at a set RPM. I bet it's a mechanical/ fuel problem stopping it at 4,800.

Are you running an air filter? Sounds stupid but we had a filter that was too small and it did the same thing. After that, we never ran one.

You also have to factor boost pressure on the intake valve, the pressure on the valve acts like a week spring. You want to run alot of spring pressure on the closed side, but you can't have too much on the open side or your collapse the hyd lifter.

And when we did the 610 it was with the 80mm turbo on the 363ci. (we couldn't break 525 with the 70mm it was too small)

You can't mistake fuel pressure for volume.

john