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.

Agreed. You actually take control away from driver :rolleyes:

Can you comment on fuel efficiency now that you have SB installed? I definitely think the lag is also built-in for fuel efficiency, at least in part. Jack-rabbit starts kill mpg. But lag is annoying.

It's a bit early for me to really say since I've just had this on for about a day. I expect my mileage will suffer somewhat until I adjust for its Jack-rabbit effects. Having said that, I do like the new feel with it on and noticed the "lurch" problem with the transmission also seems to have been addressed. The stronger, early signal seems to tell the transmission computer not to drop down too low in city driving so when I'm creeping along, the power seems to come in almost instantly when traffic moves again - no pedal lag, no transmission lag, no lurch. Unlike sport mode that forces higher revs throughout the band, the SB still allows normal D drive upshifts when you are easy on the pedal. Gunning it will get it kicking in much faster than stock.

There seems to be an expectation amongst some members that this is a performance mod and I suppose to the extent anything that improves responsiveness is a performance gain, my main reason for trying it out is not for the power or 0 to 60, etc. It was simply to experience a more direct driving response. I am very happy thus far. If you are looking for a power boost or a seat of the pants improvement, don't look to this product. However, just like the clutch delay valve, if you want a more direct and connected feel to the throttle, this might fit the bill if you can justify the price tag.

After 4 days, here are the consumption results:
Before SB: 12.2 litres per 100 km (19.3 mpg)
After SB: 12.4 litres per 100 km (19.0 mpg)

That was based on very easy, deliberate fuel economy driving. I'll do a fun drive and report back.

I've done quite a bit to increase HP on my 4.4i and nothing has had as noticeable of a difference as this.

As much as I don't blame people to be skeptical, no where does this product claim to add any HP.

I can honestly say that I REALLY like what this did to my throttle and I had a problem with how slow my car downshifted before I even knew this existed.

I do find it a little funny that people get a lot of shit for buying this snake oil, but 80% of anyone who races amateur on a sport bike puts a 1/4 turn throttle on their bike. 100% of MOTO GP and WSB bikes have them stock....Same exact concept.

:iagree:

Save yourself some money and just mash your gas pedal.

One could say the same about your smoke reflectors, LED License plate bulbs and Aero kit. I can promise you this, sprint booster will make more of a noticeable difference to your car than any modification you have made so far.

Wow!!! How can you compare something that was done for aesthetics with something you purportedly think gives you more performance???

Fact: Sprint Booster remaps throttle response to make it more sensitive.

Fact: You can do the same thing by mashing your gas pedal.

You might want to consider this to go faster too:

Electric Intake Supercharger/Turbo All Makes/Models +HP: eBay Motors (item 160501586639 end time Nov-09-10 16:05:49 PST)