Have a new 07 LBZ, first diesel ever owned. Still stock. I see all these adds for more horsepower and fuel mileage. I am using this primarily to tow a 30' travel trailer. What is best set up for mileage?  

i dont know much about the new 2007 but a air-intake and exhaust is a must before you put any modules or tuners on. they will drop EGT and RPM and give higher HP and LB.FT also increase your mileage. on the intake to save money just get the K&N filter and use the stock pipe these mods wont do a lot but will help your truck "breathe" then try a tuner. but be careful once you mod your dmax you will want more power.    

I'd go with a K&N replacement filter for your stock air box; a Banks Otto Mind programmer; a Banks Monster exhaust; and a Banks intercooler. I did all this to my 08, except the intercooler because I don't do any towing yet. I also replaced the Allison's outside spin-on filter with a cleanable/reusable unit from www.gopurepower.com - the shifting is greatly improved. The owner of the company has an 08 3500 Duramax, so call and ask him to tell you about the trans filter.  

k&n sucks so much dirt into the truck go with an afe intake  

Yep he is a Banks saleman.... Sounds to me like he has been suckin off Gale Banks thats why he loves his product so much :0 dont go with K&N if you want your turbo and entire truck to last. Go with aFe, i have always used them and they are top notch.  

either afe or s&b  

im about to yank the banks air intake out of my truck and put in am afe just because the filter with the banks kit is a spitting image of the K&N. kinda gives me a bad feeling in my stomach.  

I can't say for sure about the relationship between Banks & K&N, but a lot of companies that offer performance "packages" that include an intake don't actually manufacture them themselves. A lot of times, they're built to spec for them by a third-party vendor.