Without the SB; lag that I would perceive to have had when I mashed the pedal was a bit annoying. With SB there is minimal lag if any. It by no means a phenominalmusthaveoryouranidiot mod, however, the small nuances are very gratifying

 

I hope you all have room for another "opinion". I've owned my 545i for 16 months and put 20k miles on it. I noticed immediately that the pedal must move what seemed quite a bit before the throttle body/engine actually senses it and starts to accelerate. This was/is very noticeable (and irritating )when trying to feather the throttle for a smooth shift. That delay or lag is what the sprint booster was intended to reduce "in my opinion - because I don't have one". I never assumed that the changing of the throttle pedal characteristics would improve the over all performance of the car or produce more power. It would just reduce the delay between pushing down the pedal and when the throttle body actually opens at partial pedal/throttle.

When the poster said lag or delay in acceleration I did not assume he meant at partial pedal but when "mashing". That is a completely different phenomenon and not likely to be affected (significantly) by a sprint booster. The ability of the engine to quickly rev when the throttle body is opened to WOT is more dependent on ignition timing and valve timing assuming the gear ratios or torque load are the same.

 

I have had thsi issue since day one (4 years now) and I've complained 3 times including taking a drive with a tech to demonstarte the problem. For me it mostly occurs after 2nd gear is engaged and you add juice- there's a very noticable lag and then a powerful surge which can cause the DTC to light. I thought it might be Vanos or just how this engine comes on cam but it's most definitely there. Tech says it's the DTC engaging ever so slightly (without lighting teh DTC light) and that it's "normal". It might be normal for them but it's not for me- it's very distracting and if I thought the SB would help I'd buy it but I just don't want to spend $300 and have a useless box like many of you report.

It's another indication to me that BMW is abandoning us driver enthusuasts... I ordered the sport package, but the shifter was terrible, the CDV was aweful and the throttle lag annoying. My steering wheel is also cocked to the left by a few degrees ("normal also") and the open differential is a total joke for a "sports" sedan. My e39 528i was more "fun" than this car even with 160hp less.

I don't know what I'm going to do next time- maybe they want "drivers" only in M cars- but I tried the M5 back then and couldn't own the SMG. Maybe the M3 with 6MT could work. Oh well we'll see but I've been a BMW nut for decades.