A BMW that hasn't revved over 3,000rpm is not going to run properly after that. BMW engines need frequent redlining to keep them in tip-top shape. The M3's they use at BMW Driver Training pull harder than the M3's used privately in the cities because they are used in the manner for which they were designed.
BTW, I can't believe that you'd call your BMW a piece of shit while trying to flog it to some poor bastard on this board. Basic English grammar comes in handy too.