for more information I have purchased this and other exhaust parts for my 2000 Ram 1500 5.9 liter petrol engine. The factory exhaust is very quiet, this exhaust has a deep tone and is significantly louder than the factory exhaust but not so loud as to be uncomfortable. As for increasing mileage. This is a silencer. While this provides smoother exhaust flow, the increase in mileage is negligible at best. Anyone who says they've made significant progress is crazy about the placebo effect. To really make a difference in mileage and performance, you need a complete exhaust system. Excellent value for money and quality. Great sound on my single exhaust V8. The surface is aluminized. I painted mine with high temp paint to slow rusting and increase attractiveness. (I live in the Rust Belt.) I would definitely buy it again and would happily recommend it to anyone.