I have a 2004 F-150 5.4 3V. I have been thinking about removing the rear convertors for better sound. Can removing them be done without changing my tunes that I already have? Will it cause the check engine light to come on? I have already searched this and came up with nothing, so sorry if asking a repeat question. Thanks

 

i'm pretty sure the 04+ trucks your alright with removing the rear cats without having any cel or running problems.

 

Dont need to tune it, wont set a CEL since the O2s do not monitor them, and it will unleash alot of volume, and a little more torque. Dont do it if you have emissions and smog testing cause you will fail visually, and fail the sniffer.

Heres my removal experience.
https://www.f150online.com/forums/ex...rear-cats.html