Hello everyone I have an 05' 4.6L f150, I've recently put a 6" Fabtech suspension lift with 35" tires on it. Im having some exhaust put on it in the next few days. I'm getting flowmaster True Dual exhaust and I just wanted to know what kinda raise in gas mileage I can expect. I'm currently getting about 11mpg. Thanks for the responses.

 

I think that you mileage will be -4 mpg less than before for the first few weeks or until you get over the sweet sound!

I do not know if you will see much of an increase, but enjoy finding out. And keep the group informed of your results.

 

You won't gain didly squat with flowmaster.. I think I lost 1mpg w/ the orginal 40 si/do with the exact same driving habits.

 

Don't expect anything. It's mainly done for sound and looks. If you do happen to get ANY kind of increase consider it a plus, but don't bank on an increase.

 

in my van i went from oem single 3" to -2.25" true dual- ,if you look in my gallery-i took photo of inside of oem y-pipe-driver's side was into and impeding flow of passenger's side by 1.25"-i also used x-pipe close to original y-pipe location-i used 2.25 for tq-i iusally drive vehicle so it shifts at
~3000 rpms and keep it 65 on highway-~2000 rpms- this way i'm in the meat of the tq curve-my last 3 tanks since new exhaust wqas on-1.55 mpg avg increase what gears are you running? did you correct mph[speedo] for larger tires?that will affect your shift characteristics-i'm running the smallest body 4x9x14's maganaflows and it's loud-hope this info helps -phil-

i would not go larger than2.25" IMHO