I have a 2003 GT, 5 speed, almost bone stock. Still even has the 3.27 gears. I get around 21-22 miles per gallon, but I was just wondering if getting an off road x-pipe or h-pipe is worth anything other than the sound. Would it hurt or help? Improve mileage or hurt it? I had a foxbody and it helped it majorly, but of course they were stopped up to the gills. The car is my daily driver and I’m not extremely worried about power as much as fuel economy with this car. I’m tickled with the 21-22, but just wondering if I could milk anymore out of it. Mostly highway driving situations. Any help would be appreciated. Thanks!