Best combo for mileage in a 01Cummins??
 

:argh:I've got a 01 Dodge 2500 5.9 Cummins 5 speed 4X4 shortbox. the old owner cut the cat and muffler off, I wonder if that is something to be worried about?? I only have stock gauges and run with 3.55 gears. I just want to get the best of mileage, at about 75-78 miles an hour I pull 15-16 mpg. I had this same truck before with an auto that did about 17-18 mpg. I don't pull all the time but when I do I pull. I know air intake and a full exhuast will be a good start, past that without spending a bundle who's doing what and what is your mileage?

Welcome to the Site Tango. There's as many different answers to this question as there is options out there.

Be sure to fill out your signature so we know the details on your truck. If your runnin stock tires and don't do much pullin those gears are killin ya at highway speeds. The cat and muffler delete are fine as long as you don't get inspected, even by a cop at roadside. The two items you know abut already, the good exahust and ir intake will make the most difference in mileage right off the bat. Past that the best improvement is through foot control.

Big Hill , Gale Force Winds .. OH Wait ..... :)

RV Injectors would be a good start , And a Good Torque Converter Also Improves Fuel mileage , Painless has a new box out for MPG as well

y is rv injectors good fo milage

Seen Various Reports of RV injectors increasing Fuel Mileage

i hadnt heard that. thanks for the info dm. glad i got em in my new motor

I've just come to the conclusion that everyone of these trucks has it's own personality. Don't seem like any two respond to mods the same way. Add the same turbo to two otherwise exactly the same trucks and get two different Dyno readings off of them. Some guys talk about the Comp adding fuel mileage on certain settings but in my case I get the best mileage when I turn mine off. That's what makes it hard to answer questions like this without just making the statement first that this is my best guess.

When you get right down to it fuel mileage can be a product of about anything. Clogged air filter, clogged fuel filter, bad VP, bad LP, clogged injector, leaking fuel line letting air in, bad tranny, not enough air in the tires, softer compound tires/Mud grip tires or any of the thousand other things. All of these items listed can be such a slight problem that you would never know without extensive testing and checking of the systems.

Ive sold lots of RV275 injectors and I have got reports back of between 2-5 mpg increase with a set of RV275 injectors.

alot of it can be the driver, when i drive, i average 20 highway, 15 city, my girl friend drives it, she sees 22.6 and 19 city and she runs the same speeds i do. i also have seen that 5 spds milelage can vary based on shift points and such. best thing to do is slow down a little. i used to run damn near 80, i slowed it down to 65 and i get 20 mpg. while making 450 hp using 150 horse injectors.:U:

RV injectors are great,even if you don't get fuel mileage,the smooth power is worth the money.
If you really want better mileage slow down,works every time....