Ok, I just noticed this twice. I had my windows down last night and I was at a light way out in the middle of nowhere, and I floored it from a dead stop to about 60. I let off and when I stopped at the next stop sign, I had a awkward smell coming out of my exhaust. It does have a new cat with about 500 miles on it, so I know it cannot be failing. The smell is not rotten eggs or anything like that, it'* more of a smell I cannot explain. I do know that I have KR right now, the KR is kinda random, and it peaks at 2* max on the last 3 runs. Is the smell I am smelling the engine running lean? Let me know.