Good first mods
- A fuel pressure gauge on 24-valve trucks, where VP44 fuel supply matters. Specialists publish how to test it.
- Steering and front end: braces, stabilizers and heavier linkage. See steering.
- Towing gear: the right hitch, a brake controller, and air bags or traction bars. See towing.
- Tires sized with speedometer and gearing in mind.
What to avoid
- Deleting or defeating emissions parts (DPF, EGR, SCR) or installing defeat-device tunes on a road vehicle. EPA treats this as tampering under the Clean Air Act, and its enforcement reports cover diesel pickups specifically.
- Parts without California approval if you are in California: CARB requires an Executive Order for many aftermarket parts that affect emissions.
- Additives the manual does not call for. Cummins does not recommend aftermarket oil additives.
- Lifting without fixing geometry. Springs alone on a link-front Ram pull the axle off center.
Where this comes from
- Blue Chip Diesel: VP44 and lift pump information (PDF)
- Diesel Power Products: How to check lift pump pressure on a 24-valve Cummins
- Pure Diesel Power: Cummins fuel pressure test procedure
- U.S. EPA: Tampering and aftermarket defeat device enforcement policy
- U.S. EPA: Tampered diesel pickup trucks, review of enforcement evidence (PDF)
- California Air Resources Board: Aftermarket parts and Executive Orders
- Tiffin Motorhomes: 2020 bus chassis manual (Cummins engine section, PDF)
- Carli Suspension: 1994-1998 Dodge extended control arms
Last reviewed 2026-10-19. General information only: your owner's manual and service information come first.