Back Pressure??

[Mastirmynd]

whenever i get onto the interstate, in a hurry to merge with traffic i usually put my foot down and just take off, however when i shift from first to second to third and sometimes fourth, i hear something like a POP out of my exhaust, like a little burst of air shooting out. A friend of mine said it was just backpressure and would go away if i get a higher flow muffler, which makes sense, but if anyone else out there knows or has an opinion, i'd like to hear it, <BR>Thanks guys.

[Sonicxtacy02]

um i think your friend was talkin about a backfire which in most cases comes from a misfire in the engine. Backpressure isnt a symptom its more like a concept

[antwawn]

what causes mis fire?