Hi I have a 2005 F-150 Lariat 5.4 3v. I have a Spectre CAI, 2 Flowmaster Super 10 Mufflers, Magnaflow high flow cats, Afe Throttle body spacer.

I'm wanting to get some more power and better mileage. "Supercharger and Turbo isn't an option unless its used for about a grand" I'm leaning towards underdrive pulleys, longtube headers or "shorties if there's any problems or major modifications for longtubes" and Sct X4 from 5 Star Tuning with custom tunes for my performance mods so I would get that after I get my upgrades on.
I don't know what else there would be for this truck I don't want heads or cam or anything like that I'm only looking for bolt on's? Would the Mods I mentioned be pretty good? Is there any problems putting on longtubes? Any difference in power LT vs Shorties?

I was thinking about putting a single muffler on also Dual in/Dual out since mine is true dual maybe having one muffler would increase HP/TQ?

Any information or answers to my questions would be great help. Thank you.

 

more power is an inverse relationship of more MPG and vs versa. simple physics begines with your AFR (air fuel ratio) typically about 14.1 AFR.

lean the AFR and you get better MPG but less HP and more heat
richen the AFR and you get better HP but less MPG and less heat

 

Ok i will try that. I sent back my TBS but I got the SCT x4 installed with custom tunes. I got the 91 performance tune on now I usually run 89 but trying new things. Gonna try the 89 economy next fill up but it shows where i can change global timing, timing at wot, AFR at wot, shift press, shift at + or - miles other than normal. Not sure what i should set any of it at dont wanna mess things up.

 

From the research I've done and the threads I've read, your true dual exhaust us probably the biggest killer of power and mpg. I very much want a similar setup except with super 44 and a h pipe but until I do my 4.88 gears I don't want to sacrifice any power.

What gears do you have? Changing them can help with power and mpg

 

I have 3.73. I am fixing to do 4.88s on my mud truck it has 37s though I wouldnt figure I'd need 4.88s with 275/70's. So the x pipe should help I think. Where should it be placed? between the mufflers and converters?

 

An x will help but these motors don't seem to like dual exhausts for some reason without a tune. I'm sure you still have plenty of power, I'm just saying a single exhaust is better for performani and mpg

 

i've been doing little things to the 5.4 but x pipe will be the last performance. I need to get a paint job then im done messing with it. I have my offroad truck with a 351w I need to work on more than my DD.

 

If you have true duals, you'll pick up some power just having a balance tube welded in (making an H pipe) and it will sound better.

Question about crossover pipes on dual exhaust | The H.A.M.B.

The old hot rod trick is to paint a section of exhaust white just after the heads/manifolds and go drive. The spot that it's burned off the most is where to put the tube.