7901 WS6

iTrader: (6)

My LT1 seems to have a backfire while cruising at low speeds(40mph or less). It is all stock except I have a SLP CAI and 98 WS6 muffler(single out on Left). It only happens once is a while. But It happens only when the car is at like mid low RPM(2200-2500) and push the gas pedal a 1/4 more down than what I was holding it at. and I hear it like faint "Poof". Is this normal? I keep checking my air filters after I hear it when I am stopped to see if they are still on.

Thanks