I think the horsepower question ("How much...") always gets asked the wrong way. Rather than asking how much is enough, I'd counter and ask how much is simply ridiculous.
Case in point: I saw a YouTube video of a German builder who has built a Cobra with 1300 HP---let's assume that's at the flywheel. The video was truly impressive and the car was an absolute beast (in a cool, gnarly way). However, he had so much torque that with sticky rears his wheels developed stress cracks.
As impressive as the Cobra was, that is simply ridiculous.
Okay, so let's work our way down from there. Below 1300 fwhp, want's the most ridiculous horsepower you've heard of?
DD