Hello I have a 2000 5.4 f150 that has 4 cats. I want the obx LONG TUBE headers with the 2 (only 2) high flow cats and will run true dual exhaust WITH X PIPE and 2 flowmaster super 10s... But also have emissions test here in Illinois... Would my check engine light come on? Will I pass? If not what could I change so I could!? Please help me out here!!
THANK YOU!

 

Those cats may or may not throw your CEL. If you were to swap Magnaflow hi-flow cats in, after checking to see if the OBX cats work or not, you should be fine. The Magnaflows occasionally can trigger the CEL also, but it's pretty uncommon. I'd think about getting the kit without the cats and then buy Magnaflow ones separately. Comes out cheaper than potentially buying both.

I have the OBX kit on my 2006 without cats, and the one guy I know that had them on your body style also didn't have cats, so I can't vouch for the quality of the OBX cats, just have heard that they're not very good.

 

If you are going to go through all that, you ought to do it right and get it tuned to avoid long term catastrophic issues from running lean... IMO.

 

From what I've read the cats on the OBX kit are crap.
When i did OBX LTs i just went with the resonators. And tuned the rear O2 sensors off so no CEL. No annual emission test in Michigan..
I would honestly get maggy high flows, they will work better any way.
And a different muffler choice

 

Headers don't affect the readings on the front O2s, so no risk of running lean to my knowledge. Correct me if I'm wrong, but I'm tuned anyway, so not a worry for me.