Hey there bimmer dreamers and gearheads, I just changed out my seven year old OEM muffler for a new bright Supersprint Sports exhaust with dual round tips. The amazing thing is... my gas mileage appears to be greatly improved. I don't know if my OEM exhaust was just passed it's shelf life or if the new exhaust is that much better. I really changed because my OEM exhaust was rusted and disgusted and became an eye sore on my bimmer. Any-who, if someone wiser than me has any pertinent input as to why my gas mileage is better, please feel free to chime in and help me become smarter if that's possible. TIA