ECU = Electronic Control Unit
FI = Forced Induction (turbo/supercharger)
GM - Gun metal
JDM = Japanese Domestic Market
MY06, MY05 etc = Model Year
NA = Normally Aspirated (i.e. no turbo/supercharger)
OEM - Original Equipment Manufacturer (genuine Nissan)
PM - Private message
SC - Super Charged
TT - Twin turbo
UY - Ultra Yellow