They have a 45 day money back guarantee. I ordered one primarily for when I tow in the mountains, but I’ll post an update after I use it to see if I get better city mileage.
Has anyone added a performance module to their eco diesel? Like this:
https://www.powerupdiesel.biz/3-0L-Ecodiesel-Fuel-Mileage-Increase-p/drp-1417eco3.0.htm
Beneficial or waste of money?