ROI Series | 2001-2010 Chevrolet/GMC with 6.6 Duramax
Jake H • January 8, 2025

Please note: MPG improvements depend highly on the owner’s driving habits, record-keeping methods, fuel quality, and more. While observing increased fuel economy is extremely common after installing a FASS Fuel System, we cannot guarantee a measurable MPG improvement.


Have questions about a FASS Diesel Fuel System for your Duramax, Powerstroke, or Cummins-powered truck? Contact us today!


We’re proud to be a family-owned, U.S.-based manufacturer. From our production facility in Marthasville, Missouri, we serve diesel owners around the world.

How to install the FASS Single-Bolt Sump Kit (SK5501)_Blog Main Image
By Jake H October 20, 2025
Learn how to install our Single Bolt Sump Kit (SK5501)! Easy, no-tank-drop installation, superior fuel flow, and durable design. Click for the YouTube video!
FASS Fuel Systems: Solutions for Trucks, Farm Equipment, & More_Blog Image
By Jake H October 17, 2025
FASS Fuel Systems aren’t just for trucks! Our systems support farm equipment, construction machinery, generators, and more. Not sure what you need? Contact us today!