You most likely already know this but just in case …. the BMW's running 148 to 150 in my neck of the woods were around 550 hp. The easiest way to get a few extra/free mph is to remove everything external sticking out into the wind. Side mirrors are 2 mph believe it or not. (Mustang friend) If you use some collision wrap and close part of the grill opening, or all of it, you'll find a few more mph. All at no cost.

Les