my bad.... it engages around 5krpm (oops!...just about double the number i originally posted)... and it's just not noticeable, that's why you won't feel a 'kick' since it's just controlling the valves electronically when certain requirements are met. i dunno a lot about it but thats the bit of info i do know.... there's probably a lot more people better suited to properly answer your question with greater detail tho!
