Hey guys. I have a stock NA 89 5 speed basically stock on 93 octane. I'm running a ghetto/leaky test pipe, bosche wires and NGK irridiums. Other than that its totally stock. Every now and then if I get on it a little and run it into the 5-5.5k rpm range i can hear an occasional pop with the rpm drop. Motor runs perfect and doesn't miss. Should I be concerned? I've read that a lot of mkiiis like to do this but they were either modded or boosted. Thanks guys.