Last few times driving the car with driver's window open after stepping on the throttle to pass, an acrid burning smell wafted into the cockpit through the open window.No smell when driving gingerly. Have an F1 with tubi and stebro straight pipes on. The smell is like a burnt rubber or burnt clutch smell but there in no discenible clutch slippage and didn't burn any rubber passing after down-shifting from4th to 3rg at 50mph. Car has 5k mi. Wonder if it's an exhaust leak or some burnt carbon residue in the line? Any ideas?? Will probably bring to dealer tomorrow.