At the risk of restarting this thread and re-inflaming passionate arguments, here's my take on the SB after just installing it on my E53 4.4.

The response is definitely more linear than stock - 25% pedal travel = 25% throttle, 50% pedal travel = 50% throttle, etc. I doubt it would increase power/torque but then they never made any such claims. The pedal response feels more predictable and no longer has an annoying lag where pressing down smoothly doesn't produce the same smooth power output. It takes a while to adjust to the new pedal feel for this vehicle but it feels much more similar to my E39 M5 (without the same power, of course).

It seems newer drive by wire cars share this common trait. My wife's E90 335i also has an annoying pedal lag. I initially thought it might be turbo lag but when I forced higher revs, the pedal lag was still there. You can always get used to it but I would much prefer the linear feel the SB provides. The primary reason I buy BMW's is the close connection between driver and machine. I think SB restores that insofar as pedal response is concerned.

My advice to those considering a purchase: buy it if you want a more predictable pedal feel, not for performance per se.

My question is why BMW maps their stock pedal responses like this. Is it a safety or fuel economy technique? Or is it simply to differentiate between the M cars and their regular line like what they did with LSD and clutch delay valves? If so, I think it is a flawed strategy.