it's still realitively new and it's an expensive piece. not many people in the general public have the cash to shell out for it. the two people i know that have used it have noticed better throttle response, idle, vacuum and a little more mph. neither can really say if it was the carb. or if the other carb not tuned properly. the added expense wasn't really justified but did notice an increase over their existing carbs. might be a bigger increase in a different type of application then either one of them were using it for. ie: pump gas,540 cid and 512 cid. might be better for a bigger cid,higher compression, etc.