I have these three cat numbers written down from when I was going to re-do my exhaust. Well my taxes are back and the time is finally here. I have an 02 f-150 with the 5.4 it already has true duals but it leaks like crazy so i'm just going to have it all re-done and put new cats on in the process. But what's the difference between these three magnaflow part numbers: 94306, 94006, and 94106. They all have 2.5" in/out. And I'm not sure what pipe size I should go with 2.25" or 2.5".

 

94306 has an air tube - which you don't need

94006 is a 12" body

94106 is a 9" body - this one will be louder

 

They are the same series cat, 6.2L / 6200lb GVWR rated, and no O2 mount. The differences are,

94306 - 12" body t-304 stainless finish cat with minor resonating.

94006 - 12" body t-409 natural stainless finish cat with no resonation

94106 - Exact same as 94006 but in a 9" body, sounds near cat-less.

Go with the size of the true dual pipes, or if you want to stick with full 2.5" go with these. The 2.25" versions of these cats last digit is a 3, 2.5" version is a 6, and for the heck of it, the 3" versions last digit is a 9. To simplify it,

2.25" - 94103
2.5" - 94106
3" - 94109

 

I'm not sure what size pipes are on there but it's going to be entirely redone. So the option will be there to change size. For the O2 sensor do you just weld a bung in after the cat?

 

Isn't the 94036 number a cat with an O2 bung already in it? Just curious but wouldn't it be easier to use a cat with the O2 Bung already in it?

Kev

 

Yes, mount them back after the new cats.

Easier? yes. Better? Not always. Some CELs have been known because these trucks monitor the cats really well. Re-mounting the O2s after the converters ensures the catalyst has filtered everything and then the sensor can read it. The cats with the O2s equivalent to the 94306 cats is the 94136.

 

OK that makes sense. I have also started researching this. I am a fortunate owner of a truck with the 4 cat system. Maybe later this year I was thinking about replacing with just 2 high flow cats.
Kev

 

Note that Darren has the same model year as you and he deleted his rear cats instead of doing high flows.

 

Mine has 4 cats as well. I just think it'll be easier to expalin to a cop why there's hi-flow cats instead of just pipe lol.

 

Wow, you have cops that would put that much effort into your loud exhaust, lol? But seriously, I can understand your concerns regarding inspection. Really just depends on what your local laws and ordinances are.

 

Yes I deleted my rears entirely and kept the fronts intact since the front cats in 2004 and 2005s contain the main catalyst to burn and filter gases. The rears filter with only a bit of rhodium, and mostly sound resonating packing. Replacing four with two hi-flow cats will be healthier outside though. My truck will not pass an emissions filter test because it smells a little cat-less.

 

^ mine won't either...