i would probably recommend getting the aftermarket ecu, or even a piggy back.
injectors u probably wont need, i just decided to get them cause i got them at a bargain price but if u want to do anything like that you will definelty need the aftermarket ecu.
other things you can do are get bigger cams, bigger valve springs, get stronger pistons (all on the list for me!!) etc.
my Apexi Power FC was put in the same day the NOS was tuned in.