04 F-150 Exhaust

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Im looking to put an exhaust system on a new 04 f-150 with the 5.4 liter. I was wondering if anyone had any input into this. I know a guy at express muffler who does the custom pipe and was thinking about putting a spintech on it, but im not sure if that would be the best set up. I knowit would be atleast half the price of a Borla kit.....your thougts?

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[shrek]

I would put a dual exaust on it and spintech is a good muffler..............

Shrek

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do you think that dual would make that much of a difference? I have always ran mine out the side, for looks and performance, but im not sure if thats what i want to do yet.

[shrek]

I am building a 04 F-150 8100 truck right now.........we asked the ford engineers what the best thing would be to do with the exaust. (not knowing if or how much backpressure the new 5.4 needed)

Their reply was simply "big and two"-----------so we took that to heart....

Shrek

[transformed]

good to know. thats always good when you can ask the engineers

[GBoyer]

I just put an airraid intake system on my 04 5.4 and it makes a huge sound differents, but didn't notice any performance out of it...

-Greg Boyer

[roach]

you cannot legally put a dual on an 04 ford. you cannot go dual from the engine back becouse both pipes will not be of the same length. on the newer cars the gas tank, fuel lines and brake lines are on the oposite side of the current pipes. on older and race cars, they build dual exhaust from the engine to the rear. on newer cars you can only build dual exhaust from the muffler back - not much performance there. if in theroy, performance is getting out smoothly and quickly, run a short system like you said out the side and your exhaust is out. with the dual from the muffler back, it still has to be pushed out thru even more pipe than what the factory intended to begin with!!!! spintech is OK, but all they did was try and improve on a desighn that already works great - the flowmaster. that is what it is trying to simulate. i have done many of these and i DO NOT recommend the duals on the newer cars. definately yes on race and no smog cars, but no on the newer rides.

[shrek]

Why can you not legally put duals on a 04 F-150??? What law governs the length of the pipes, or where they are run??

Shrek

[roach]

there is no law that governs the length of the pipes, but california SMOG, EPA, and CARB govern the smog laws here. in order for you to legally modify an OBDII exhaust system you need to be equavalent or higher than what the factory installed. in other words, if you have a V6 motor and want to change it, you cannot put in anything smaller than the v6 in it now. you can only install bigger (i.e. a bigger v6 or v8. then you have to smog according to what engine you installed regardless of what year the car is. so if the motor is a 96 and the car is a 86, you smog according to 96 standards, which means you install everything the 96 had including the exhaust cats. so, for the 04, there is nothing in the "STOCK OFF THE DEALER" truck that came with true dual exhaust from the showroom that the smog guy could punch into his computer. some of the 04's had a dual in dual out muffler, although i think only the lightnings had this. you can do someewhat of a dual there but like i said, for the price people charge you are wasting you money. which race truck has exhaust going all the way to the rear bumpers????? performance is getting your exhaust out smoothly and quickly. remember, exhaust gasses dont just come out becouse they see daylight, they need to be pushed out (backpressure), so short exhaust has always been the prefered choice on trucks. i try so hard to talk people out of a dual exhaust on newer trucks. leave all your pipes alone, they are almost a 3" already, get a 2 chamber flowmaster, then just dump it. done. performance with a good tone. and by they way, the 04 has between 4 to 6 cats on them, try and remove those for a dual exhaust and still be smog legal. pm if you need any help. i always like helping the off-road crowd versus the rice rocket crowd that always comes into our shop. (nothing mean intended to all you honda owners, i'm just an off-road junkie

[shrek]

FYI......the 2004 F-150 with a 5.4 does not have OBD II...........It has a new system called CAN.

Also.....If I rememeber correctly it had 4 cats, just like the previous model years.

"so if the motor is a 96 and the car is a 86, you smog according to 96 standards, which means you install everything the 96 had including the exhaust cats. so, for the 04, there is nothing in the "STOCK OFF THE DEALER" truck that came with true dual exhaust from the showroom that the smog guy could punch into his computer."

I have always understood the law to be that you could only intall a engine the model year of the car or later, and you were governed by the laws of the year of the car. How would they know the year of the engine, anyway. Unless they were to run the block numbers??

Also, would it only have to have the correct emissions of the applicable year, not necessarily the "stock number of parts."??? I have never seen a smog guy count the number of cats a truck has, only make sure it has one..........

Shrek