almost none

you can hear it rumble in the city.... but on the highway you cant hear it....(a/c on and windows up)

 

I agree with Jeanyus....

most or all of my mods will be mostly for MPG....
Somethings I may do for the fun of it or for a little more towing power.... but its directed more towards MPG...

I've got the volant CAI with ram air tube on its way...(thanks Bryan!)
If I could find a used UD pulley set and maybe some mid-length headers and an ORY, then a tune I think I would be at where I would want to be.

 

if ALL of your mods are going to go towards MPG then you are going to have a relatively short list but if you are so concerned with it then get a prius as a DD and use your truck for when you want to feel like a man

 

I can get 16.5-17 on the highway if I keep it at about 65, any higher and the 4.10's just kill the milage. However on the same note if I drive it like I stole it It will get well into the single digits. Average about 13.5-14mpg with mods in sig.

 

I recently sold my 04 dmax and bought a 06 ccsb 4wd with the vmax pkg. I tow a 7500lb trailer on occasion and knew I'd miss the dmax doing that. I was right, Went from 15 mpg towing to 12.5. I average 16-17 in town and can get 20 at 63 mph on a straight road. I just can't stay at 63. 70-80 is more the norm and the 4.10's do take a toll. I think without a trailer I'm darn close to the dmax mpg.
When the truck was all stock I could set the cruise at the speed limit (55) on a certain stretch of road and get 22 mpg. After a slightly larger 17 inch tire and heavier rim and a cai it dropped to 19.5. with a cat back (B&B) exhaust and a westers tune I'm back to 20.5 on the same stretch of road.
I need every bit of power for towing, and the 12.5 was not all that bad, with my performance gauge showing an increase of 65 horses with the mods and breaking in, but I've sacrificed some mpg to do it, and it seems it went with the install of the cai and the larger tires/heavier wheels?
with gas at $3.20 gallon I certainly find myself babying this truck more than any I've owned. I'm about ready to change the oil to mobil 1, turn off the dic and drive it like I stole it. If I can't get 20 mpg on a regular basis I should at least start enjoying the darn thing.

 

Last weekend I towed an all steel trailer and reset my MPG guage... going up there I averaged 70mph and got 14.3mpg (it was also over 100 degrees...I think it was 103 or 105)

On the way back, with the same trailer, a washer, dryer, 2 person hot tub, tv, kitchen table and chairs, a good size dresser and some other small tables and misc stuff....
I got 15.4mpg @ 65 mph (it was around 80-85 degrees on the way back)

Dunno how 5mph can make that much difference.... maybe the 20 degrees cooler air helped....but I dont think it could help that much

 

i got about 18-19 going on the hwy for about 3 hrs. speeds went from 70-85. i reset the DIC when i filled up with gas and then hoped on the freeway 5 min later, but i got on it to 90 then backed off. when i did that same trip and kept my speed at 65, it got 22mpg. my city is like 13mpg

 

get a custom operating system and speed density tune and command your air fuel ratio at 16.5:1 at cruise and it will get you good gas mileage..with all the mods i had on my 5.3 the highest ive seen it is 17.8 on one tank of gas..and thats with me froggin it a few times

 

OK I filled up the other day, got on the freeway and drove 65 MPH to Sacramento and back, about 65 mile round trip, about 5 miles of it city driving. The DIC said 20.4 MPG, maybee this thing gets better milage than I thought.After burning a full tank of gas it worked its way down to 14.2 (acording to DIC). I figured my milage with a calculater and it comes up with 12.8. My DIC is a liar.

PS I would rather ride my bicycle than drive a Prius.

 

When I bought my '05 Silvy SS it was 450 miles away. I drove it back home and had to be easy with it cuase the tags weren't exactly legal. I stayed around 60-65mph and it was ALL highway. On that trip it got 17.5mpg or so. Since that trip it has never got that gooda gas mileage again. Most of my driving is highway and I was averaging around 15.1-15.5 depending on how I drove. 15.5 was driving easy with cruise on 65 most of the time. Since I put the headers on my average has went up to 15.7-16.3mpg.

I still don't understand how some guys get 20mpg in stock or relatively stock 6.0L's. If I could get that mileage I'd prolly have a heart attack like EXTREME.

I prolly have one of the worst combinations for gas mileage though. 6.0L and AWD.