I've got a 94 GS-R i/h/e (GReddy Evo exhaust). Anyways, for the past 6 months that I've had my exhuast in, it's pissed me off that when I'm slightly on the throttle (like, accel pedal depressed only about 1/2cm), the exhaust burps/farts/rumbles... is this a side-effect of not enough back pressure on the B18C?

I notice it most when I let off the throttle and I'm deaccelerating... for a split second it farts like twice, then that's about it. Any ideas/knowledge?