Just depends on how low the vacuum is. If vacuum at idle is really low then you have to run open loop at idle and go closed loop at 1500 or 2000 rpm. The Sniper doesn't have any problem handling race cams or even open headers but you have to adjust the tune. The out of the box tune won't work. If you know what you're doing it only takes a few minutes to dial in the tune. If you don't know what you're doing then it could take much longer.