So ive been contemplating on taking out 2 of the 4 cats on my truck, and replacing the other 2 with hiflow cats. At the same time i want to go all out and buy some headers too. I was wondering if anyone has installed headers on this body style f150 with the 5.4, and if so how hard was it? Also was it worth it in the end, as far as power gain and sound? Thanks!

 

If your thinking of short headers, no gain. You will lose torque.
As for cats, no gain there either unless the ones you have are restricted from age or a serious missfire that melted them internally.
Your waisting money and hassle for no gains.
good luck.

 

Well ,I have no proof but. Buy eliminating the 4 stock cats and replacing with 2 high flow cats, Your volume will increase by about 3 or 4 times!
But don't wast your time and money doing that unless you are installing Long Tube headers!
With long tube headers and 2 high flow cats you will see an increase of 30 HP and 35 torque!

Phil

 

Respectfully Phil,
....On a 'stock' motor such as the 5.4, It cannot pump or convert air to exhaust at more than 500 cfm at 5000 rpm if that much.
....The stock cats will flow that amount and more unless they are restricted from their normal flow rate.
....A 3 to 4 times flow rate increase is not even possible even with no cats in line.
....A 30 hp increase is very doubtful on a stock motor.
....HP is torque times rpm divided by 5252. For example a 35 lb ft increase at 4000 rpm would =26.5 hp. If everyone could get that much from an exhaust change on a stock motor, that would be a very popular mod to do and become well known.
....You would have to increase airflow through the motor at the same RPM.
...With a stock motor at 'normal' useage and that won't happen.
....The intake manifold and heads are too restrictive for any extra air flow to support that much extra power and the cams peak out too low in rpm, as well.
....If, by your bottom line info, you are running a modified motor, you certinely need headers for your application but the same is not applicable to a stock motor.
....Referring to flow 3 or 4 times and 35 hp on a stock motor is not being honest to a less well informed poster asking about a stock motor.
....Your application is not anywhere near his.
....Your entitled to your opinion but I must say otherwise having many years of experience with many kinds of race engines on gas and alky both NA and super charged, carbed and FI.
....Bottom line is what you get out of header with your modified motor will not translate to a stock motor to that degree.
....Sorry to call you on it. I'm sure your not going to agree. I've explained some of the reasons why.
....Further, if FORD could increase hp that easy they would not have to work so hard with cam phasing and other tricks to keep getting more hp as the years roll by without re-designs to get the power increases.
....The 4.6 is no longer produced for the F150 such that a 5L is the base v8 now due to the weight increases and buyer desires along with 3 valves etc to get the flow support.
Take care.

 

I never said 3 or 4 times the flow rate!
I was simply referring to the volume of the sound going that much LOUDER. LOL
So,,,you think it might be flowing MORE in order to get a sound increase?

 

who makes long tubes for our trucks, other than the uber expensive Dynatech?

 

Patman03screw (patrick) or something like that installed my long tubes, I then went and installed the resonators and everything else. he said theyre a pain in the ***. but with a body lift its a lot easier.

 

4.6 or 5.4?
For the 5.4 ,anything listed to fit a Lightning ,fits the regular F-150 also.
You can get OBX on ebay. About 500 for good stainless headers.
Or for cheep steel headers you can get them on summit racing (pacesetters) to fit the 5.4 and I think the 4.6 also.

 

mine were OBX SS long tubes with SS resonators. i paid somewhere around 460 for em