I've done the windshield on both of my E34s. I spent a bit over US$1000 on doing my preferred car the right way, genuine glass, with new genuine trim strips. But it was only about US$200 on my other one with a generic locally made glass with a generic rubber trim around the edge. I'm glad I went with the options that I did because it gave the right result for each car. There is a very very slight wind noise on the generic one, but not something that's ever going to annoy me.