Has anyone had their cars tested to see actual HP, if so how did it compare to advertised HP.

 

On the dyno you should see around 435rwhp.

I'm assuming the engine makes 510 at the crank and a 15% drivelosee.

 

While you can find plenty of dyno results on this board (including the ones from Renntech you posted) the trick is that you are forced to make assumptions about driveline losses. I haven’t heard of anyone pulling an engine to measure on an engine (rather than chassis) dynamometer. My personal view is that the percentage driveline loss for such high-horsepower engines is a little lower than people think, meaning that people slightly overestimate crankshaft HP from their dyno runs.