There are a couple of reasons besides pipe bluing to get rid of the AI system. It causes a series of muffler explosions on hard deceleration and a muffler can stand to blown up only so many times before it starts losing its internal bits or splits open, usually in the presence of a policeman looking for an excuse to give you a ticket. The other reason is that lighting fires in the pipe is likely to be really bad for the exhaust valves.
Then there are the additional hazards such as burnt personal parts and the chance of starting fires with the overly heated pipes.
