While installing the Diablo sport I came across a o2 sensor option. From my understanding of it you can eliminate the 3rd and 4th cat because the diablo allows you to do that by telling the system it is there and working. Is this correct????? If so I would only need one cat per side right????? Any info would be great. Thinking about doing the headers and cat system next. I have the dual extreme from gibson installed and like it. Thanks for any help with this. .

 

That is my understanding as well. You can also accomplish this by installing O2 eliminators... a plug that tells the ECU you're good to go.

What this means is that you still need the two cats per side on a registered road driven vehicle by federal law... what you do is up to you, though.

-Kerry

 

I did an exhaust on an 02 F-150 with long tube headers, and eliminated the cats. The owner purchased an SCT programmer that also had the ability to disable the rear O2's, and the truck runs great.
If you use a tuning device to shut the rear O2's off, then you don't need MIL adapters for the rears, just unplug them, re-tune, and go.

 

Thanks for the feedback. I will likely run one cat per side and use the diablo to confusr the system of the back O2 sensors. What are the MIL adapters? Thanks

 

MIL adapters plug into the existing rear O2 sensor wireloom plugs, this is what I what speaking of in my previous post. They mimic the O2 sensor when it is functioning correctly, the ECU senses that the rear O2 sensors are A-OK, when, in fact ,they are gone.

-Kerry

 

Thanks for the reply. Now I just need to get this all done. Are there any other mods that need to be done by going with the headers and high flo cats?

 

If you disable the rear sensors I believe you don't need any cats. I've seen many trucks like this.

The front cats are pre-cats, the rears are the main cats.
The rear O2 senors just tell the ECU if you have cats, and if they are working somewhat correctly. That's why the MIL eliminators work - they just send the voltage that the ECU is looking for (slightly different voltage than the front sensors), they have no bearing on the operating parameters on your engine. Your front O2 sensors are responsible for A/F ratio control.

I run Magnaflow high-flows instead of the main cats, and no pre-cats (I gutted them so it looks like they are still there so I pass the visual). I run all O2 sensors. No CEL. And I pass CA smog, even with the blower and fuel system mods. I just had to make sure that my main cats were still hot - drove around then right onto the emission dyno.

Seems like you're in good shape.
If you run the factory collector (not true duals) then definitely get a new one. The factory one is quite restrictive.

 

I live in Iowa and we have no inspections. My I have is the extreme dual gibson exhaust cat back. K&N Cold air intake. I want to install headers and high flow cats. Eliminating two of them leaving one high flo per side. I would not have true duals due to the Muffler having a single inlet and and dual outlet. So I could maintain the Y pipe unless there is one that would be better. Thanks for the input on this I will be doing this very soon. Your recomendation would then be____________. Thanks

 

I had a Magnaflow collector before I went to duals:




You can get them for about $30.

 

So this collector would tap in to the muffler from the Y pipe right?

 

Wherever you decide to meld two into one, that's where this thing goes.