Guess my Hp and Tq

I had estimated the output with a simple math equation, based on what is reasonably possible with a radical build: 408 (cubic inches) X 1.25 (efficiency) = 510 HP which is just about what the dyno read. It would be unrealistic to expect much more than that for any such build. I had a very radical 273 and based on ET and mph it only managed about 1.12 HP per cubic inch, so I believe you are way ahead of the game, especially considering it was a first run without any fine tuning. Anything over 500 horsepower in a 3200 lb vehicle will dip you into the 10 second bracket, so try not to be too down in the mouth, now that you discover you WILL need a roll cage!