Am I supposed to hear the engine when idling? I had a bunch of work done, i.e., elbow intake, intake actuator, oil change, micro filter, air cabin filter, oil filter, thermostat, coolant flush. Runs wonderful now and much more quieter than when I purchased it used four months ago, Sounds like a buzzing from the tail pipes while cold idling and once warmed in the front somplace -- sounds like a tape is caught in the fan sound. I checked the fan -- it is fine. What is that? Views anyone????