Yeah, what Brian said. Stock exchangers are continuosly cooled by air and probably made of thicker gauge metal.
BB's (especially those w/o heater boxes) will be more glow-prone in case there is slight missadjustment in AFR and ignition. I suggest leaning the mixture and advancing ignition slightly at idle.
There is probably lot's of unburned fuel that is continuously combusted in the tubing.
Thank you for your time,