Dodge

6 spd manual trans, after market 4 inch pipes. only getting 15 mpg, wondering why ?

If all you have on the truck is a monster exhaust this is a problem. you need a bigger air box and a diffierent intake. then chip it. since you removed the factory equipment and started to add performance parts you lost mileage. now you have to finish the mod process to get you mileage back up. stay away from bigger injecters. it also depends on the way you drive and tire size. pick up a copy of diesel power magazine they will answer alot of you questions