LBZ Dually Bad MPG

[4230JohnDeere]

Hey guys I have an 07 classic with the LBZ it's a 2wd dually with regular old street tires. For the first 9,000 miles I had it it was completely stock and has only gotten 13 mpg. For the last 2,000 miles it's had a edge evolution cts2 that I keep on extreme and a 4" down pipe back that is strait piped. And according to the dash and the cts monitor I'm still only getting 13 mpg. According to the edge my balance rates are all within spec. Is there anything I can do to get some kinda mileage out of this truck??

 

[Dalyfarms]

I have a 06 dually 4wd with 312,000 on it it has just recently dropped on mileage to about 10-11 mpg, I was getting 16-17 I am wondering if the fuel is not worth a darn myself.

 

[CentolaCCSB]

Try changing fuel filter

 

[TheBac]

Try hand-calculating your mileages first, and not just one tank of fuel.

Winter fuel does get worse mileage.

 

[4230JohnDeere]

I've changed my fuel filter 3 times in the last 10,000 miles and hand calculated says about the same 13.1-13.2

 

[Porno Joe]

Is that city or highway or mixed?

My dually gets 12-13 on 100% city driving

 

[ty_LBZ]

Any smoke from tailpipe?
I get 16-17 mixed driving