Corner entry speed isn't going to change regardless of power at the rear wheels. My old engine made 491rwhp and 497 rwtq and it was very managable during a fast autocross. The new engine is 75hp and 54 ftlbs stouter at the flywheel. It's now a handful. My opinion is you will need to be a much better driver the more power you put under the hood. How many 1000hp drag cars have you seen run 12's?
Ryan Mathews in the DSE car almost taking out the cobra on the road course is a prime example. That car makes South of 500/500 at the tires. I doubt you see DSE with 700-800hp. I don't think the chassis can handle it. Meaning, decent traction in the first three gears. Let's not forget I'm running R888's and all the events will be 200 treadwear. Do I think Stielow can handle 800hp. Yep, but most of you can't. Putting down that kind of power in a straightline with a well prepared track is a different ballgame than a road course or autocross. I wouln't want anymore power.....there is a point where you over power your chassis, tires, and you run out of talent.