It ran rich when it was all choked down from the stock mufflers. Now it can breath. It is not bad at all. The sound stays the same as you increase in speed. The performance through the power band is amazing. I dropped 35 lbs and gained 7 HP. All these guys spending money on pipes and this is the way to go. Kept the stock headers, chrome heat shields, and can put it back to stock to trade off at any time.