i have heatwrap on my downpipe, it smokes @ lights as well....it doesnt burn at all theres just some smoke. I only have about 350 miles on my car but I would of think anything that wants to burn off would have within the first few miles of boosting hard/putting heat in the motor. I am using summit racing heat wrap, maybe theirs just sucks ass. I always carry a fire extinguisher just incase