The 5.4 in my 99 f250 is not up to par for me. It runs slow and gets horrilbe milage. I was consitering doing a few things to get a tad bit more power. I was looking at a throttle body spacer, air intake, and possible tuner. How much of a differance does this make? Any recamendations for the air intake? Also I run 85 octane, what kind of differance would 87 make?

 

The spacer wont get you anything. My friend and I have installed several mods on his 02 F-150/5.4. Each was installed one at a time and each mod has produced noticeable results....here's the list:

Custom catback/side exit
underdrive pulleys
Cold Air Intake kit (el-cheapo off of ebay)
Shift kit (Factory Tech)

We're going to install a set of headers here soon, and then he'll be looking into some aftermarket tuning.
He runs 87 octane (recommended) and has tried 93 with no noticeable results, though the track times will tell all.
Being that your rig is a bit heavier, I'd say a set of taller gears will definately help.

 

Supercharger"headers:custom Tune; Total Bitchin Power

 

Agreed....if the funds are available, there will be a significant increase, as per the seat-of-the-pants-dyno.

 

A good programmer like the Diablosport Predator will make a nice difference.

 

PI caliber heads are even better. I guess they apply to 99 5.4L's.

Go no further and you've done well.

The early Tritons and the RWD unibody derivatives were not "all that".

 

Get an intake, throttle body, and exhaust. That'll get you some more power. A spacer (I have one) is a waste of money. You can fool stupid people into thinking you have a turbo at certain rpms because of the sound they make, but other than that they're useless.

 

i did the k & n and took the air silencer out and also got an el cheapo exhaust from summit racing.com (summit muffler 3" inlet offset/ outlet) clamped it on and stuck the exhaust out the side.

i noticed a big difference doing these upgrades... my next upgrade will be the underdrive pulley kit.

i also run on 87 and 89 1of evry 5 fill ups to help clean out carbon build up.

 

Supercharge it. Best bang for the buck. You can also look into gears. I have 4.56's.

 

you have 4.56 with what size tires- auto or stick?


nevermind - just looked at your gallery!

 

I have efans, tuner,tbody, headers, true duals & a K&N fipk. I gained good power & it gets 18.5 mpg on the highway if you stay around 75 mph. I may add underdrive pullys next. The efans were a good boost in mileage & power.