There is a timing "blip" when the car shifts, but it is so brief that I doubt anyone could detect it. If the torque difference is big enough and you do get wheelspin, only then does ASR gets involved. As far as just an engine power curve, virtually every M119 I have driven has displayed a bit of a flat-spot in the torque curve between about 1700rpm and 2700rpm. It isn't lacking power by any means, but the power increase is not linear through there. Once you hit 3000, and especially 3500 when the valve timing advances, it goes crazy right up to (even slightly past) redline...

I've heard from a reliable source (c'mon Michael) that some of the aftermarket chips help with that flatspot, but I've never been able to get personal verification.

If your car is shifting short of redline, it could feel like there is a flat spot that isn't there. Gear ratios are chosen to work with the engine's power curve...if you are shifting outside of spec, you will lose some performance. The bowden cable is an easy adjustment on a M119 W124. Look just behind the airbox and the firewall. You should see a metal rod with two press-on ball/socket ends. By adjusting the length of the rod you can adjust the shift tendencies. Start at spec (the two nearby plastic arrows lining up) and work from there. I recommend about 1 full turn past spec for daily driving. Up to 2-3 turns past spec for track. The motor will not go past redline (at least no more than any other M119 going to 6300 or so) no matter the adjustment. However, if you want to know for sure, just shift the car manually. Hold it in 1st with the shifter until 6000rpm then tap the shifter to 2nd, then bump up to 3rd. Do this all just right and it should only take you about 14 secs tops. At least the testing will be fun...

Hope this helps,
Lee