I just installed the Sprint Booster in my R53 and I felt the difference immediately! Yes, it's expensive, but I hated the delayed response with the throttle and the Mini dealer couldn't fix it even with a flash firmware upgrade. So I was willing to pay for this booster.
Anyone that hasn't tried, need not criticize it. Let me tell u that it works and the throttle response is very sensitive now. As soon as u step on the accelerator, it goes! No hesitation!" Review from Northamericanmotoring.com "We installed one in my buddy's car (15% + CAI only) and the difference was amazing. Pulling away from a light was much better and the top end felt the same. I understand how it works and no, moving the seat closer doesn't do the same thing. I tried that before we installed it. When you move the seat closer your foot is now at a jacked up angle and makes the car harder to drive. The SB just made the car funner to drive. It "feels" like the car has more power. I know it doesn't but you sure think it did." Review from Northamericanmotoring.com