Open up a thread in the n54 section, I'm sure there are some solutions. Just adding that I'm FBO and I get better milage than you stock!
Back on topic: OP, Endras sucks. Try BMW Toronto. I argue with Endras all the freakin time, but I hear great things about Toronto. WG rattle plus whine is likely cause for replacement.
edit: Just saw that you're out of warranty. IMO, you're SOL. I recall a thread where people were pushing BMW NA for a 10yr warranty on turbos, but don't remember what became of it. Sorry OP.
Last edited by Tzu; 05-28-2012 at 10:37 AM.