Is it REALLY possible to run 800hp odd on a standard supra engine (obviously with different cams) ?

I know people in the USA who claim to have it but i know several people who have imported a lhd supra from the usa thats 900hp, dynod it and its only 500hp so its hard to tell fact from fiction!?

Not got many years to go untill I can do my supra build, and if I can run big power on standard engine then it saves me £20k!