I did the normal search route and browsed through many threads but didn't find the answers, so here we go...
1. On the Edge Evolution wire harness, what is the extra 4 pin plug next to the OBDII plug for?
2. I have an '05 with four cats. I plan on removing the back two. Anyway, why did Ford use the four cats in '04-'05, then switch to two in '06+?

 

1. NO CLUE
2. I know in my 08 the CATs are much larger than the previous years- per my Muffler guy... Maybe the 04-05s were smaller and needed more? No real good answers to some of the choices FORD made on these trucks ie, the 2 piece spark plug issue, VCT solenoids not accessible unless head covers are removed, etc....

 

1.for wideband sensors
2.my 05 only had two but it was a late 05. And 06 had two due to larger size of them