Good question. I want to piggyback on his question.
Does putting a racing seat (i.e. Recaro) lower your position?
(in short, will my head be far enough away from the roof for me to wear a helmet comfortably?)
'86 325es (TURTL3): PJ peetsa hawler
'87 535is (BADWATER): almost done... really.
'86 325e (GRN HLL): DD/show/rocket
'04 x3 3.0i: Wife's Bimmer (manual, woot!) My BMW Blog