I'm planning on upgrading my 98 M3's suspension. I've heard good things about H&R springs w/Bilstein dampers. As I've been looking through catalogues, I see that there seems to be 3 "flavors" of coilovers available. There's an H&R kit, a Bilstein Group N kit and an HRB kit. I'm sorta confused as to what the differences are. I AutoX about twice a month and use to drive a 3rd gen RX-7; so a stiff ride is no big deal. I'd like to budget around 2k. Could someone explain the differences in the kits and/or give reccommandations.