i have a 1999 Super Duty with a 5.4L. I have hardly any backpressure in the exhaust because i have a straight pipe. i know the way to fix this is a high flow filter, or cold air. However, cold air is expensive, so i was looking at getting a k&n high flow filter. There is a specific part # for my truck, but i was wondering if i have to get that specific filter, or if i can get any filter that has a 4in inlet on it? Any help on fuel filters is much appreciated!

 

As far as I know all available filters are high flow. Some of them just stop less dirt than another.
I have severe duty Ford filter on my truck and after 70,000 miles it still is not showing on the filter meter, while oil testing shows no dust (silica) in the engine.

 

What? Where did you here this?
First off, no. Not true.
Second: Stock air filter IS cold air. Look at it.
Third: A high quality paper can flow WAY more air than this engine would ever need (unless revving to 8K rpm with forced induction and different cams...)

 

Agreed!! Save your money and put some ford DP plugs in it.. Don't waste $$$$.

 

Your exhaust problem isn't because you are running straight pipe. I think the problem is the exhaust piping is too big. A 3" system with a 4" tailpipe on a stock 5.4l with headers is way oversized.

 

The 3in exhaust is stock for my truck, and the tailpipe is only 2ft long so I don't think that would make difference...

The way I look at it, lots of output with low input isn't working, so how bout more input? More air and more gas will balance out with less back pressure

 

Nope, sorry. There's a whole lot more to it than that....

 

At some point the laws of thermodynamics come into play and cannot be ignored! If you are just stuffing air in and allowing unlimited air to flow out you have upset the factory designed scavenging effect that all naturally aspirated engines rely upon to clear exhaust gas out and draw fresh mixture in to cylinders this throughput is a major source of efficient operation and shouldn't de jacked with too severly, or your performance will fall off very noticeably! You are at the point where you will need to add fuel and modify timing to compensate for the higher throughput in other words get your tuner! I recommend 5 star with the SCT platform it's truly superior! Others may have different opinions! Mines right!.....lol
Jim & fat Monty