Keep in mind it's probably a California emissions model so can anyone tell us if the cat/muffler is shaped differently on Cali version ?
Its not.
The difference with the cali models is that the evap solenoid is used and there is a coal canister next to the fuel tank to recirculate fuel into the tank. Nothing else is different.
An exhaust wouldn't make a sling catch on fire, there is nothing in that area to burn like that.
He either had a short somewhere which would kill power to the spark plugs like he said it was missing revs, or a faulty fuel line.
I am really not a fan of those quick connects but it would be surprising that it would pop off and engire keep on running and catch fire.