no joke... aircraft paint remover... spray them and leave that shit on about 10 mins...

takes EVERYTHING off the surface (oils, clearcoat, paint) and i'm pretty sure it gives you cancer as well... Win win as far as i'm concerned.

Seriously though i used that shit then scuffed them up with some 300-ish grit, and sprayed some duplicolor sandable primer. lol i havent put the paint down yet but i'm positive that they are going to come out awesome.

edit: I got the shit at pep boys but anybody should have it.