HP out of N*
I read somewhere that GM has pulled over 1000 hp rom the 4.6 32V Northstar. Obviously with some major mods. The problem with ours is that we have front wheel drive. If I'm not mistaken you can't pull too much HP from the engine unless you make major mods to the tranny and drivetrain. I'm sure it could go another 100 hp or so with our current setup but after that it could get dangerous w/o mods to the other components.
So, yes, this engine is capable of serious HP but with our setup we are limited.
BTW, had the car at 145 mph for at least 6 min straight here on the autobahn in Germany. There is a stretch between Berlin and Leipzig where it'* wide, straight, and it was a dry beautiful day. It ran smoothly the whole time. I have run it steady at 118 mph many times and it can do that all day long. Mine is an early 2004 model. Built in April-May 2004.