I was considering removing my resonator in the process of replacing the muffler. If you do a search on the the term resonator, most people think it is too noisy in the passenger cabin without one, although some think it is fine.
The thing that make me decide to replace the resonator were the comments by Gale, an engineer, about the function of the resonator. You can read what he said in this thread. There are other comments about the resonator issue sprinkled through out the thread even though it is more focused on the muffler.
http://www.bimmer.info/forum/showthr...ight=resonator
Dinan chip, Bilstein sports w H&R, RD sways, RD strut brace, 750 bushings, Zimmermans/MetalMasters, O.E. M Pars, Eisenmann muffler