I have 1994 Honda Accord LX. Last year I install new cat-back system. A mozart muffler with 2.25 inch piping. I also have ractive header. The catalytic converter is honda stock. I also put a new oxygen sensor also. When i went for an inspection I failed. What chances a honda failing inspection? But anyway, my mechanic inspected the engine for 8 hours. He couldnt find anything wrong with the car. NOTHING. I only fail when the car hits 30-40 mph. In high speeds its all good. But one thing i really do need is a full tune-up. I have 109+ miles on my car. Can anyone tell me whats wrong?