Fass Fuel Pressure Spikes

[Foster#17]

I just Installed my new fass 150 yesterday and got my fuel pressure gauge hooked up today and the fuel pressure spikes from about 14psi up to about 18psi and I cant figure out why? Seems like alot of people have this problem... I already have the snubber valve with the fuel psi sensor so that wont fix it. It only seems to do it when sitting still idling, When im driving it will go up to around 24psi I believe and come back down. I dont understand why it fluctuates so much but It doesnt seem to be a problem, It runs Great!! Before the fass, I had a 0-60mph time of 4.8 and it brought it down to a 4.0!! I cant imagine what a bigger CP3 would do... Im hoping to have picked up a little time at the track this Friday! But If anyone has an answer for the pressure spikes that would be great!