what he means is... not human error... mechanical error.... slipping trans, similar to slipping clutch or belt will only hold what it will hold. your 1000hp goal may look like 650 with a slipping trans even though its a 1000hp setup..I think we will get accurate readings. This is a hot rod shop and they dyno hundreds of high hp cars.
imo should worry about not blowing a rod through the block after 3200rpm more than hp numbers.
but.. good luck