rebumping this because i never got a good answer.

 

I took mine off on my 03 5.4 when I put the 3 inch flowmaster super 44 series and no light came on

 

What do you want us to say?

Just do it and see what happens.

 

The answer to the, will the CEL light come on is maybe. It depends if the front cats are up to par. If they are not, it will trip the rears for cat insufficiency. You can do the Gotts O2 and eliminate any question that they will come on from the bat, or you can wait and see.

 

thanks!