You know... I have found thru my Autobahn "testing" that a stock 135i (mines a N54) is just as fast as an e92 M3! Atleast until the 135i's speed limiter kicks in at 155mph. The last one I "raced" it was too much for the M3 driver. He really was mad.
It got me thinking... if I had a BMW perf kit... I bet that 20 PS and extra oomph(TQ)... would mean a 135i would be about three car lengths in front of a M3 at speed. BMW doesn't quote a whole lotta of PS(HP) but they do show the acel times are much faster WITH thier perf kit. Esp when they quote in gear acceleration which is real world types of autobahn racing.