I have recently installed a cold air intake with high flow filter (Kand N) on my 92 Miata. Since doing so, I have noticed that when I shift at higher RPM's, say around 6-6500, I hear a noise that sounds like air pulsing out of the exhaust. It is not a loud bang like a backfire, but more like a giant puff of air? Otherwise, the car runs great. Anyone have any ideas on what this may be? Iwas concerned that I had leaned out the car, butthis would seem to be a too rich problem???. I will be installing a new high flow cat with Borla Dual shortly, butI am curious of what this might be. Any ideas?