so my cats are rattling so i thought this would be my chance to get high flow cats since they dont cost too much more. i have the 4.6l engine so idk if i could still get that loud *** deep sound. plus im getting horible gas mileage do you think by replacing my stock cats that i believe have never been changed will improve gas mileage cause im gettng around 8 miles city. will putting high flow cats turn my check engine light on. plus wat high flow cats do you reccomend

 

First make sure it's actually the cats that are causing the problems and not something else. Could be just a heat shield rattling. Changing to hi flows is fairly simple: buy 2 Magnaflow 94106 universal cats, Remove all four stock cats, weld in high flows with the rear O2 an inch behind the cat. Do not touch the front O2 sensor location. To best account for the modification, proper custom tuning will be needed.

 

What he said

 

X3

 

Hey,
I have a 97 4.2. My Cats are plugged baaaad.

Im doing the same setup tomorrow with 2 magnaflow high flow cats. My question is... Is one inch from the cat to the o2 sensor mandatory? Right now it is about 3 or 4 inches away, will that be good enough or will the flow be too fast past the sensor?

Thanks =)

 

I had all 4 replaced on my 02 5.4 and installed by the exhaust shop just last week he installed em about 4 inches below the top o2 sensors and just before the bends on the factory pipes not exactly sure the distance before the bottom sensors but somewhere between 2 to 3 in so far no codes and very pleased with the sound improvement

 

Would it be due to higher flow that you would want them closer?

 

I'm interested in getting high flow cats, I also tought about just removing two of my cats and guttin out the other two. Would it be the same as just getting high flow cats or no?

 

ive been thinking about geting high flows

 

I guess you have not look at replacing your cats with OEM...high flow cats are a whole lot less ... not much more. Do what the guys told you , you will be good to go.