I have the Jackson Racing version. What i didn't know when i bought it was that you can not engage vtec any lower then about 3900-4000. So i got screwed there cause i didn't understand it. So then i got the thing hooked up and was running it at about 3900 rpm and i was told by a respectable person that i wasn't getting any power down there. So then i was like WTF was the point of buying this thing if the stock engagement is at 4400??? so now i just got it at about 4100. If i were you save your 350 bucks and buy something else. I know i would if i could. And if someone could let me know if i really am losing power by having vtec engage at 3900 it'd be nice to here it from more then one person just to be positive that thats true.