I got my series 40 flow saturady and put it on in the stock location with stock pipe and ran a turn down right after it in front of the axle and it sounds awsome...but anyway i know i kept my foot in it the first day i got it, and today coming back from school i noticed it drank more gas, i mean i lost about 5 mpg or so, and my truck is all stock but the flow...Did anyone elses do that or is it just mine?

 

5mpg?

How are you calculating this?

You should'nt of lost anything, 1-2 TOPS with your foot in it.

 

i had the same muffler put on my 99' 3.O and the only reason i noticed a decrease in my mpg was because for the first week or so i could not keep my foot of the skinny pedal...now 5 mpg sounds a bit dramatic? how did you come up with this number?

 

i was on the F when i left for school this mornin...13 miles away...i came staright home and i was almost on a 3/4 tank?...didnt think i dogged it at all today...

 

called a friend with a 98 2.3 ranger auto and he took his off cuz of the way his drank gas...he's running straight pipe with turn down now and gets twice the gas mileage as with the flow....

 

This makes me wonder if my poor gas mileage was attributed to the Flowmaster 40, instead of the IAT mod like I originally speculated.

 

back pressure...

this is why ill be taking mine off soon and going to something a tad bit quieter, i also think it makes my truck sound like a pissed off escort with a fart can.

 

Its not that bad...i dogged it today in town and showed out alil and it got better, but it really did drop...a good bit, friend of mine said run the pipe over the axle then turn it down so the pipe will help pressure out

 

something else must be wrong or the gauge is off. There is no way the Flowmaster will cause even a single MPG decrease unless [like myself] you drive a bit harder because of its sexy sound =)

 

thats the only thing i did was the flow...gas guage had a new sending unit put in about 3 weeks ago and it works fine

 

Must be the way you're driving. I had a 40 on my truck for about 6 months. Single in, duel out. No difference in MPG at all.
I took it off because it was to loud for me and I lost bottom end because the pipe I.D. was to big.

 

You CANT go by the gas guage, its NOT accurate.

Try this:

When you FILL UP with gas, re-set the tripmeter to 00000
Drive around until you are close to E, or when the LF light comes on.
Fill up with gas, then divide how many miles you drove by how many gallons it took you fill it up again...

Thats the correct way to calculate MPG..

 

yea but i never have enough to fill all the way up, body shop i work at dont like paying me much...LOL, its getting better, guess it could jus be the muffler breaking in...

 

Well just try it with a 1/2 tank then...

Reason i say let it go down to E is becuase the lower you let the needle go down, the more accurate your mileage readout will be.

 

i found some leaks and ran another bead around it and put a 1/2 tank in it and drove 50 miles and the hand did not move, unlike when it was leaking...