nicknaz: i can adjust the width of he post. in fact, i like center mounting more just because it keeps the slim long lines of the z4..but might experiment with the width regardless. as for height its adjustable up or down about an inch. but for a wing to be useful it has to match the line of the roof or come close to it.
Moo: 20" wheels are for street..will pick up a pair of wheels jus for track and swap on track days and stuff