You should talk to your tuner and see what he recommends. I can't tell if you are out of injector head room or not. If you can log a pull including injector duty cycle you'll be able to see your answer on that end of things.
600+ hp is an epic jump from 300whp. I didn't see that you specified whether you were on a 2.0 or 2.5L... but at that power level you'll be giving up some serious reliability and daily driving fun. I'd re-evaluate your goal there personally.