was it possible you were getting some tire slippage on the dyno rollers? that could throw things off. I have seen cars smoke the tires on a wheel dyno before and you cant possibly be accurate with that happening...even still, almost 20 more ponies on the ground over a stock GTP is nothing to sneeze at. Thats a far cry over what a stock GT is putting on the pavement. Car must feel like a rocket (this is really taunting me btw...Ed sent me a price on parts for top swap...very tempting)