Alright, now I was told the front cats are meant to cool down alot of heat, then the rear cats are after. I may have found someone to do my two cat system, and I was gonna get the 94306, or the shorter 94106 which I was recommended to, but since the 94006 and 94306 are used by alot of people here and noone has had any real complaints I may stay with those. Only difference is the 94106 is 3" shorter ( 9" cat overall, 94306 and the rest are 12" ).

But anyways, is that true that the front cats are involved in handling heat? and converting my 4 cat to a 2 cat system without getting re-tuned would be bad?

 

The front cats are there to start working quickly after a cold start-up, to get hot and start scrubbing the exhaust before the main cats are hot enough to function.

 

Ok, so your saying two hi-flow cats will be fine without reprogramming? I cant afford to F my truck up I'm depending on it for alot so I wanna be very cautious with anything I do so you can see where i'm coming from.

 

you guys have this all wrong...the front cat is a reduction cat and reduces NOX with the material rhodium, the rear cat is an oxidation cat and reduces HC and CO with the materials platinum and palladium. you can replace 4 with 2 if you get the proper 3way cats that have an O2 sensor bung in the middle of the cat between the reduction and oxidation beds just like the 05-current F150 has.

 

I think I was mistaken with my post.
Now that I think about it, when I replaced my 4 cats with two high-flows, my exhaust guy put in OBD II cats that had additional Rhodium in them.

However, I had a 97...and the high-fows that I got didn't have a sensor bung in the middle. Newer trucks may need this...my bad.

 

So your saying If I go with the Magnaflow cats that have an O2 sensor bungs in them?


Yeah, all of Magnaflows cats are OBD II and CARB certified. What my plan was, was to get the 94306 cats ( no bung sensors ) and have the OEM sensors mounted before and after the cats the same distance the OEM pre-cats are. Very confused as to what I can do now.

 

If the o2 sensors are before the precats and after the back cats just leave the sensors there and install the 2 hiflows. Thats what they did to mine.

 

Thats what i'll have to do. Since the sensors are so distant from the cats as is I'm hoping all will be ok. My OEM cats have no sensors in them so I would imagine thats how its supposed to be. If not i'll have a CEL to deal with.

 

Just make sure you dont change anything between the engine and the first sensor. Anything after that you can do whatever you want (as far as performance and tuning)

Might not be emissions legal, but wont jack your truck up

 

Alright then so I should be alright. I dont want a CEL to deal with, but I could probably cough up money for sims if I really have to..

My area has a visual, but I could most likely work something up to get 1 pair of cats stuck back in for the inspection day, or have the rear set gutted and have pipe fed through and install. I dont have emissions atleast.