I don't have a BMW but I have been searching to see if anyone has used the Vibrants 1792 resonators and I stumbled upon this thread. I'm trying to reduce the drone in my car right now. I have an 2012 Sonata and just got CP-E's new exhaust and it sounds awesome on my car. The wife though doesn't care for it much because it has a lil drone in the lower rpm's when accelerating, but hardly any if I'm coasting and not on the gas. So I was thinking about adding the 1792 resonator to the rear section of my exhaust. From what I gather from this thread, it should help me out a lot.
On another note, I figured I could help you guys out as well. Has anyone tried using the Magnaflow resonated X-Pipe. I think the part number is 11386. I had a G35 coupe prior and this helped me out A LOT. It reduced the drone and got rid of all of my rasp due to my test pipes. I think that and maybe the 1792's would help out a lot form your car as well. It gave my car a more deeper tone as well. If you YouTube G35 Injen exhaust magna flow you should find my car. It has Hawaii plates. I have a before and after video that you can compare it to.
Thanks for all of the great info and user reviews inside of this thread!