i suddenly love my trucks set up .. i mean damn.. i get no less then 16 city and can average 19+ on long highway trips.. my milage improved somewhat with my new flowbastard.. gosh i love my 3.55 ls

on another note how do you people drive? i never have to go above 2k rpm when im acc.. and i do above 75mph at 2k rpms.. hell i do 90mph at 2500 rpm's.. so yea i really love my rear end

 

That's really weird. My roush exhaust I just installed over the holiday's seem's to be getting the same MPG as before.....................

BAD!!!!

 

My MPG was around 17.2-17.5 for the first 1,500 miles then all of the sudden I can't break 15 with just a K&N and a flowmaster muffler. Now with the edge I'm getting about 15.5

I was thinking my soft bed cover might be causing the problem and I might take it off to see how the mileage reacts.

I believe my problems started after the autospring was installed. But over 2mpg lose seems a bit extreem for a slight change in areodynamics.

 

Yeah before the lift and tires I pulled in around 14-15mpg, now I consistantly see 11-12mpg. But the mountains of WV kick me down to about 10 in the winter when travelling to Morgantown.
Bottom line is its a big truck, with or without mods. When you saw 5.4L on it you had to know you werent going to see 20mpg. It hurts getting bad mileage but like many have said its something we all should have known from when we bought the truck.
That is a sick drop in mpg though and not normal. I cant see the muffler being the cause but maybe the computer is all wacked out now with the new muffler and giving you a rich mix. I would give resetting the computer a shot.