I'm looking to possibley upgrade my sound system in my 2001 E46 325i with. It has the Harmon Kardan sound system. Although it sounds pretty good, I'd like to get a system with better SQ and better bass. I already have a 12" infinity kappa perfect sub powered by an Alpine 2 channel amp. I'd like to keep the speakers b/c it looks good with the car, so do you think it would be ok just to replace the head unit with an aftermarket (looking at Alpine head units). Anyone insight would be much appreciated. Thanks!