My local boy Ryan just had Turbo Mike (also local) swap out his On3 kit to Mikes custom turbo header kit and picked up a couple HP:
He "only" did 620/650 before the piping swap, fixing the degree on one cam (it was 6 degrees retarded) and new rings as the first turner ran it a bit lean.
Its a forged bottom end, MHS Stage 2 heads, MHS/Bullet Stage 2 turbo cams, 70mm/68housing single turbo making about 20lbs. We are going to test swapping an Edelbrock/6061 combo shortly as well to see if we can pull some higher RPM.
Mustang, manual tranny, 3.73 gears, and 400lbs of help to sit on the back trunk to keep the tires from smoking on the dyno. Should have some pictures in a couple weeks on the website (its in the articles section)