ok so my truck has 4 oem cats on it 2 pre cats and 2 regular. could i eliminate the pre cats and still pass emissions?

 

It has 4 cats for a reason: to meet certain emissions standards. Can the truck function without the cats? Yes. Pass emissions? No.

 

x2 buddy our cats are different from all the other makes, thats why we need 4, and they didnt just throw 4 on there cuz they felt like it, they have a purpose, lucky for me im not in a emissions place so i cut all 4 and got 2 hi flows!!!

 

I thought the hi-flows pass emissions to, unless you're in commiefornia

 

your right, if they are C.A.R.B certified or what ever which mine are

 

Actually your 2 high flows do the exact same function as Ford's factory 4 cats. The late model F150s have only 2 cats. It is simply reduction and oxidation. You can do both in the same cat, or have separate cats for each action.

NO high flow cats are legal in California on an F150, period. If they were, i would've had them on years ago.

 

Actually, CARB stands for California Air Resources Board. It only applies to California. CARB certified cats are legal on certain vehicles, but those vehicles must first be cleared by the CARB for high flow cat use. The Ford F150 (any version) has not yet been certified.

 

ohh ok thanks for clearin that up i had heard that if they were CARB then they were legal in california, guess not, and to bad ford isnt certified for that huh why is that

 

If you remove the cats you may need a tune to remove a check engine light. Some people get one and some dont.

 

I have been told that you will need to tune your engine differently if you take off or put different cats on. is there any truth to that?

 

i didnt have to, maybe on the new f150's

 

Tuning the computer to know what exhaust diameter its running helps performance minimally. 2004 & 2005 trucks rear cats are not O2 monitored, and resonate all the sweet sound. I chopped my rears out and only running the pre-cats. No CEL, much better sound, rpms are in the same levels, no smell, still technically has cats.

 

Darren,

How do you pass emissions in PA? I want to replace my stock muffler with a Flowmaster or Magnaflow but I was gonna leave all four cats. I figured I would need them to pass PA. inspection. I am not looking to spend a ton of dough and the wife doen't like loud exhaust but I want to open it up a little. If I can pass inspection, I'll take off two cats and change the beast of a muffler that is currently under there. Just wondering.

 

lol sorry darren im gonna take this one for ya,

he doesnt have emissions

 

I have none, God made Hybrids to compensate for my pollution. Even here in Cali, I still pass smog. lol