so quick question. not sure were to post this. ..i am in the middle of a rebuild. i have a 13bt s5. ported with pinnapple ep2 templates. stock turbo with a FMIC. intake and exhaust are upgraded. msd box. the ECU im running is a redom(re amemiya). so the boost is up and the igniton is up...i have a walbro fuel pump and was wondering what fuel injectors i should use. any suggestions?

I would definitely upgrade your secondaries. 750 cc might be enough for now, but if you ever plan on going with a bigger turbo, you'll be wanting 1600's.

its hard to say, but aftermarket Japanese ecu's are tuned to specific cars setups. I would probably try 550/720 combo as that is really common there. Don't go to deep into boosting without a wideband/dyno run. Keep in mind Japanese gas is 98 Mon and has no ethanol content.

yeah i think im gonna go with the 720...but on the other hand i really don't wanna buy twice...do ya guys think if i bought the 1600 before i upgraded the turbo that it would flood the crap outta the engine. or do you think the ecu would keep it in check

If it can be tuned for the 1600's, then it would work. If not, it would be way too rich. I'm not familiar with that ECU.