This is my second Sprint Booster (Thanks Jason!) My first was a V2 SB that had 3 settings, off, street and race. Like another post here, I had mine on a tuned Mini Cooper with a 6 speed manual. The stock throttle response was crazy slow on the Mini especially when comparing it to the last "wired" throttle control car I had. It seriously transformed the feel and response in that vehicle making shifting much smoother and making quick acceleration feel as it should. The V3 SB takes a major chunk out of the lethargic throttle response and the ability to have more adjustability on the newer version is really nice. I've been tweaking it here and there but for now I've kept it on the green 7 setting. I agree it's pricey, but since this is my daily driver, the SB is going to be the only modification I do to the engine since it really helps the driveability.
I was on the fence for months reading threads and researching as much as I could about this mod before I got off the fence. This was mainly because I never owned a drive by wire vehicle before personally. I was also afraid this was just another one of those performance chips that all over eBay that are nothing more than a resistor or something that does very little in the way of performance other than some that just advance timing a bit. This device completely changed the feel of my driving experience in this car, which had plenty of power, but just didn't feel as fast as it should. Now, every time I get in it, I'm happy with the performance and it now feels like it should. The cool thing is that you can tailor the throttle response to suit your driving style. I tried several settings, one at a time, and left them for a couple of days to evaluate before moving on until I found the sweet spot for me. For me personally, it was the best money I've spent on any mod so far, other than maybe the exhaust, which also added greatly to the driving experience.
This was the missing link that brought everything else together, and I'm sure most just assume (like I did initially) that it's just a snake oil product. I like it so much that if it ever broke, I'd HAVE TO replace it immediately, lol!