Springs and wheels

Looking to lower car a little (2009 750LI) and get new wheels. Any suggestion on Springs? I was thinking Vossen CV4 20" Are 20's the right size to go with or would 21's be better?

If you lower it, just get Vossen 22's. 20 is too small.

For the springs, get H&R from tirerack, and use lowering link for the rear air suspension.