I still haven't been able to drive my 540 very much because I only yesterday got the tags transferred to the car. But in the brief driving that I have done, I've noticed that when I double clutch my downshifts, the engine barely revs at all when I blip the throttle. On the other hand, my 2003 Audi A4 3.0 (which is for sale, by the way) is much more responsive when I briefly stab the throttle. I know that the Audi has an electronically controlled throttle. Is the BMW's mechanical or electronic? And what might help it rev more easily? Just a lightweight flywheel?

yes, your throttle is by wire. A big ass flywheel combined with the slow response of throttle by wire makes for notoriously slow throttle response.

Thanks very much. Maybe I'll have to look into a lightweight flywheel and/or a chip to address the throttle response.

Is there anything you can do to significantly reduce the lag in drive-by-wire cas?