My trouble came from the fact that the problem didn't show up until after about a month after I'd installed the headers so it was not my first choice for trouble shooting and it really sounded like a small exhaust leak because I didn't lose any power or it didn't seem to misfire but my hint was it did tend to back fire when you let of the gas pedal off from time to time and it was starting to get more frequent that's what had me looking at a possible bad ignition wire or spark plug.