Originally Posted by jsmonet
Just FYI, that's afterfire, otherwise known as little pockets of unburnt fuel igniting in the exhaust. Backfiring is a far more serious issue usually requiring, at the least, a new intake manifold after it happens
Overrun/afterfire is no big deal.
Your definition of afterfire is backfire...
Backfire happens when you run too rich and unburnt fuel ignites in the exhaust..its perfectly normal and fine if you're catless. Just have to be careful of the O2 sensors.