Mccoynut, how tight are your rubber window seals to the front posts? I have a small whistling on the passenger side and found there was a slight gap between the roof window seal and the piller. Would not leak when it rained, but I guess the air pressure driving would force its way thru. Just a thought. Good luck.
S. Maykowski, Columbus MS.
My '99 Z3 Alpine White 2.8L Speed Buggy