I have extractors, 200 cell cats, x-pipe, dual two & one quarter inch pipes and just two mufflers. I am really happy with the sound, quiet enough around town but when you floor it, its loud and has definitely improved performance. This is on a 302 Windsor, not the 5.4 motor, but the lesson I learnt was to go a little smaller in diameter to aid scavenging and leave off the resonators that most add after the two mufflers. Definitely add an X-pipe as well, it helps smooth out the sound and maximise power. Have a chat to Best Exhaust & ask for Chris. He has been doing this for 30 years.
https://www.bestmufflers.com