Exhaust Issue
 

Just throwing one out here in the dark, is there any reason why one of my pipe's gives off a ****-load of black smoke and soot and the other is always clean? I've had issues with it before but no one ever solved it.

its the single pipe split to a Y then dual out the back right?\

thats because of the Y one pipe is more of a direct shot for the exhuast to flow, thus more flows that way.