So i have this off-name brand exhaust that comes with a silencer. I like to alternate every couple weeks or so with the silencer on/off. Everytime i go an extended amount of time with the silencer on, when i take it off I'm getting metal sand/carbon dust build up.

Any ideas what it is/where it's from?

b18b in a Delsol, i'm not burning any oil and i'm still getting a good 30mpg if that means anything...

Thanks in Advance

 

its coming from the can, and the metal tubes itself, most of it is from the can, the packing material will weaken over time and rattle out of its holes causing a buildup of crap.