I did the ACV mod by blocking the vacume port, reversing the diaphram and leaving the spring out. If you roll off the throttle from a high rpm run it pops like crazy when the revs get low, regardless of pilot screw position. I've got a 45 PJ installed. I figure the valve is shut with the diaphram reversed, so having the atmosphere port open shouldnt make a difference. Any ideas? Or anyone that has done the mod and had sucess?