Yes doing a burnout out holding the brakes will get alot of heat in the rear brakes and the clutch. Stock clutches don't like alot of heat. Install a line lock and that won't be a problem.
That is what he said in his post. It doesn't make anymore peak power it just carries it out to 7500 rpm whereas the stocker falls off after 6500. So basically if it was a street car it won't be any faster up to 6500. It will allow you to spin the motor higher, which in turn will allow alot more...