Have had a lot of commits on the set up of a D-1 procharger on a Ram Jet 350, but when the vehicle is at idile, WOW, everyone says due to the procharger. Hit the gas and hold on, just the sound of power being made. At idile when it is warm you hear the gears slapping, the tech I talked to today also said, "Yep thats what it does!", who has one and do you have the same noise. Was in INDY at the track this weekend and only found one guy with a vortec charger on a 98 Z and just a whistle, anybody got any thing!!!!

 

Not sure what the slapping noise is, but my vortech is REAL loud at idle. I was thinking maybe your idle is rough and could cause a quick accel/decel of the blower but your FI, so I doubt you have a rough cam.