My question would be what fuel management are you gonna use? SAFC only- stay with 450's.
VPC/ARCII 550's
EMS- who cares- you've got it under control
I really suggest to most people running 550's if you can on any of the aftermarket turbos- 450's should have come stock on the car- and if you are really pushing the 9b's then you need 450's.
Take it up a step with the flow and I'd suggest 550's for 13G-15G cars- 15G cars that are running with different heads and cams- I'd suggest 720's. It doesn't hurt to have more fuel if you can tune it.
I know it seems kinda odd- the larger injectors cause tuning issues (mostly timing) but We've only got a little bit of decrease tuned in for the 450's on Jayson's car and we're still on stock turbos! We need to seriously start thinking about FJO's and other widebands as NEEDED mods- especially for those running hybrid ODB cars. Too many of us bite the big one for tuning issues.