i responded with help in yout other thread....
look here and well take it from there....
according to apexi site...g20 will use the same N3-a wiring diagram as a b13/sentra-nx....tho im not 100% positive....
i used the n3-a wiring diagram on my nx,and should still have all my pinouts and diagrams if you want some help....
http://www.apexi-usa.com/manuals/electronics/safc2_wiring.pdf
PAGE 26 of 60 has what type of ecu pinout well be using....
PAGE 28 of 60 has the ecu pinout.....
then ,what i did is i tried to find EXACT wiring diagram -wire colors and went from there....
now are you also trying to use the NEO to change your cams too?