hi,
there are some known gotchas when using the powerfc djetro. you have chosen to ignore all of those warnings but ill recap them for you anyway.
as you are dealing with multiple throttle bodies you have to be careful of the placement of the map sensors. if its not done properly you may face tuning issues.
most good known workshops who have done a djetro GTR should be familiar with how to set it up. if they havent' dont a djetro before then be prepared to wait and have $$$
it will take longer to tune than the afm equivalent ljetro version. youll need the optional parts as well, map sensors, loom, and fittings. any of your apexi resellers can source these for you including www.nengun.com
as the powerfc djetro is a 2d map ECU once you are on max boost that you have set on your GTR the load axis never increases.
this will reduce the number of usable load points, not by a massive amount but it will. 3d ecu's like autronic can scale against the TPS for a 3rd dimension to give some more accuracy.
but again once on max load, generally the TPS is nailed too but it would help out on light cruise / light load.
the install for the djetro kit has some specific documentation and wiring notes so be sure to read them correctly and make sure the installer knows what they are doing.
the retail apexi software is a basic cut down FC pro software so it just allows map read and copy so its somewhat limited and a big flop for the $500 AU that it costs.
you are much better of buying fc datalogit from www.fc-datalogit.co.nz and using that instead. this will give you complete control, logging, external inputs etc
and last but not least there is no apexi powerfc djetro pro. you can either have pro or djetro, not both. apexi in their super cool drag car run a "secret" powerfc firmware i suspect which is djetro and pro versions in one firmware. so i suspect you want normal djetro powerfc and not the pro version.