Check out 6'7 Gopher Rodney Williams, arguably the best dunker in the draft,  who recorded a 42.5 inch vertical at the NBA combine show off what he's capable of doing with his 42 inches. Yeah, I know that sounded kind of nasty but nasty is the best way to describe his dunks including a 360 from almost the free throw line.  Yeah, he had a whole foot in front of the line but I've seen guys do that on standard 1 hand dunks and receive credit for doing a "free throw line dunk."