I just filled after running my first full tank with straight pipe (no cat or muffler, 4") and I got 15.1 mpg. My last fill up with the clogged muffler still on I got 13.4 mpg. My Aero is on the way so I will have it on by the end of the week and hopefully that will help some more. Just thought I'd let you know.

By the way, after driving about 400 miles with the straight pipe and I have noticed a loss in low end, but I'll take a loss of power and more mileage. Hopefully the Aero will help with both.

 

Good to know. I was thinking I was getting better mileage than that on my stocker! Is 15mpg the average for the 5.9? I don't have that many miles on mine so I haven't tracked the mileage trends yet. I should get to know this better after spending $120 filling the beast up yesterday!

 

You probably are getting better mileage. I think most everybody is getting more than 15 mpg, but there are a few of us that are not getting 15 mpg. I have been getting 13-14 mpg even on the highway, but recently found out my cat and muffler were clogged due to a massive turbo failure that happened when the previous owner had it. I'm hoping adding the Aero will give me another 1+ mpg.

 

expect another 1~1.5 mpg after the aero install (& it breaks in with heat cycles). that's what I saw after the install. you will get more low end torque without a doubt. put it right after the downpipe where the cat used to be (or should be). If you want another boost... consider the ATS intake manifold... gave me another .5 mpg and a noticeable bump in low end torque.

 

nice to know you got a gain. . .heck, my mileage hasnt changed since adding my 315's. . .17.7 last tank

 

My truck is completely stock with stock tires and I got 18.012 MPG hand calculated with about 65% and 35% HWY. My wife commutes 100 miles a day (from which5miles is in light traffic)and she will be driving it this week. Hopefully we can get 20 or better MPG .

 

Aruba1, Is your truck 2x4 or 4x4?

 

I'm getting 14mpg in town, mixed 15mpg 75% highway 17mpg and all highway @ 75 19Mpg.

Also when I was pulling a 16 foot trailer with 6000 pounds of material in it most times was getting 14 mpg mixedon long runs.

 

Drew, your lucky you didnt take a hit... I suspect the manual tranny is what is helping keep the mpg up.

 

I was wondering if I went bigger but stayed with the skinny ones would I get better mileage too.

I guess I need to get Drew figgure out what my 3.83 would be with 315's, since he went from 411 to 3.83 final w/ 315's