What's going on
 

Okay for a couple of months now im hearing a cokcokcok sound inbetween shifts coming from either my super charger or my belt. When i take off easy it does not make and noise between shifts. nor does it when i have it floored to the mat at the track. In these cases there is no noise what so ever,but when i take off from a light or froma roll i give it about half throttle and then let off alittle so it can shift and when it does it makesthat sound. There is no ticking noise like detonation at idle or at full throttle the only noise i hear sometime is thatsound when i hit it alittle and then let off some but not all the way. IS this a case for an auxillary idler pulley? what exactly does that doPlease help!!!!
My mods to date: 99 red lightning
Single superchip
4#jlp
90mm mass air
cold air induction
oil breather
boost bypass
and still in thebox lakewood traction bars Will put on when Jersey finally start to get above freezing

Every ford pickup ive ever rode in did this. Not saying much though. My truck does it. This is due to the fan belt slipping, or so i am told.

what should id do too prevent this from happening. Is this a majpr problem or should i get a new belt.