Not the normal type of exhaust question, but something that has been sort of been bugging me and i suppose i want to know.
I have a straight through centre section with a 4" backbox (yes i know 4" is a bit chavvy, but it was cheap and i cant afford anything else until a few months. And with the standard backbox it sounded terrible) I still have the standard cat on though. Of course it is quite loud but when im slowing down or changing down a gear it does tend to pop quite a bit, now sometime when i back off the throttle it pops quite loud, almost like a backfire.
So, 2 questions really, 1 being curious is, what actually causes it to do this? Unburnt fuel i take it? Or so ive been told.
And the 2nd question is, is this doing any type of damage at all?