I have a friend who would like to add a 'chip' or programmer type aftermarket hop ups to his 08 LMM. He (like everyone else is looking for better fuel mileage and still able to tow his 13k Fifth wheel).

I bought an 06 to duck all that new emissions stuff. When you add the programmers do you pull the DPF and related emissions stuff? I can't imagine piping that performance THROUGH the DPF!

I don't know anything about these at all. I am just asking, doing a little research to help him make a better choice! Any suggestions on a programmer or performance enhancers for the LMM?