apexi neo !

[ace-rx7]

I have got a pfc, but also have a neo colour display, i have read up a little and its a boost/fuel controller ?
 
the question is do i need both, when pip mapped the car he said its just a monitor and is not doing anything, so i was going to sell to a friend, but when i unplugged it, the car would not start, so plugged back in and all fine. I traced the harness back and its spliced into the ecu loom:Grrr  agian can i just pull it out and reconect the original wires ? will this loose any settings on the pfc ?
 
all advice gratefull as i need the money for different upgrades  and the wife has said that i can only buy stuff if sell some stuff 1st