I was wondering when puting injectors in an eclipse gs-t if you have to get a new mass air flow sensor, or if you have to get it reprogramed. Also can i get some suggestions on what a good injector brand is and what size should i get, im going to run around 16 - 18 psi.

I believe it is nex that has all the stuff you want.  They sell all the sizes (that i can think of)  and also the kits usually come with a relocator for an O2 sensor.  Don't quote me on this but im pretty sure you don't need a new one.