Actually blaupunkt is one of the best stereo companies out there, but on my e34, nothing special was required. I have a pioneer something head unit and and vr401 crossfire amp and 12" bmf crossfire(BEST MONEY CAN BUY)
DON NOT BUY SONY XPLOD- ITs awful.
1990 535i 5 Speed +[E.A.T. chip/Powerflow intake/Tri-flo exhaust system/Strut Tower Bar/Smoked Signals/Pioneer Head Unit/Crossfire vr401 amp/12" Crossfire BMF sub/eyebrows/18" alpina replica rims]+
6 cylinders, 5 Speeds, 4 Doors, 3 Pedals, 2 Exhaust Pipes, 1 Ultimate Drving Machine