Not sure if this is related to my turbo or not, but it didn't start happening till I put on the turbo kit w/the Borla catback. When the car is cold and idling I can put my hand behind the tail pipe and some little specs of black liquid spit up on my hand. Doesn't smell like oil or gas. The top part of my rear bumper above the tail pipes will also start to turn black after awhile, doesn't get really bad for a couple days if I don't wash it though...is this something to worry about? Car seems to be driving ok. I am running pretty rich, hoping to lean things down w/the PMS pretty soon...what the heck is the stuff spitting out of my tail pipes though?