My Car smokes a bit too (white smoke)....Started after I went catless stage 2. I was worried about it being coolant. But it doesn't smell like coolant and is intermittent, plus coolant levels haven't changed. As of right now it just seams like the nature of the beast. If you're really that concerned keep an eye on your coolant level, run it with the radiator cap(generic term) off, and check for bubbles, or you can get a test kit that will tell you if you have exhaust gasses in your coolant.