Ok so here in the next month or so i plan on redoing my exhaust. I know im going with a magnaflow muffler y-pipe and cats but I need to know which cats I should use and if I was going to replace the 4 oem cats with just 2 highflows how should I have the O2 sensors setup so that it doesn't throw a CEL. The truck is a 2002 f150 4x4 with the 5.4 thanks

 

Replace all 4 with 2 magnaflow 94106 cats. Have the shop put the o2 sensors directly behind the new cats.

 

You mean the rear o2 sensors correct?

 

or if you cut out your rear cats you wont throw a code

 

Correct. Leave the primary sensors alone.

 

Ive read with cutting the 2 rear ones out there is a 50/50 chance of a code being thrown. I dont want to mess with that so im just going wit the safe route and doing 2 high flows.

 

So let me get this straight. If I do 2 94106s could I get the fronts gutted so it looks stock and not have to worry about a CEL?

 

^ NO!

Replace all stock cays 4 with a pair of maggie cats. No CEL should follow.