: : If I'm correct the "short" block is the engine block without the head and all that stuff. Max speed is limited by the computer. The 850Ci is capable for over 150mph and the 840Ci is about 150mph but the US speed limit is about 138mph in every BMW !!! I belive even the M3 and M5 are limited !!! Try Pioneer or some other independent BMW parts source they might give you better price for the CD. I'd think the 350USd price range is fair and the 600 is too much !