Like patrick, I don't get great mileage with the single, cat-less exhaust system. Cherry bomb straight through muffler. Don't think headers will make that much difference. Lean burn though, I don't like that idea. Right now with the carburator problems I am having, even with the carb running lean, it isn't going to make that much difference. I thought about pulling the engine/transmission and putting in the new 5.7 hemi with the eco system. Power and mileage with the new engine would be sweet. But, that adds more money to it. Maybe the 3.5 v6 from a wrecked charger/300m. Mmm!