it is adding a resisitor inline but its a varible resistor so your not running around all the time with it on. you get a pot switch (like a volume control) and it allow you to change it. from what i've heard you keep turning until your engine raises the idle about 300 rpm or your engine starts to ping (then you turn it down abit)
it only give about 5 hp peek power but does give you enough ooomf.
do the zetec in the contours have vct? from what i had read sounded like some had and some didn't
