my exhaust

:mad:i have a 93 integra ls with a theremal reaserch and development exhaust. and sometimes when i look in my exhaust theres black oil substance. is it motor oil or something else this is my first car so im learning

is it kinda powdery? carbon builds up in the exhaust and its black and once u get it on ur hands is pretty hard to get off, cant just rub it off. As for oil, if it were i would think ur cat would be dead since oil is flamable and a cat operates at around 1200 F so it gets damn hot, so i dont think it would be oil