You should be fine then. Keep in mind more water flow will just increase the probability of killing the ETM from the water that gets blown past the butterfly shaft seal, so if you are not upping the boost levels then stay where you are at. The higher flow turbo at the same boost levels should reduce the backpressure some which will make the current spray even more effective than it was before.
Depending on which Aquamist kit you are running, and the actual flow of the new IPD 4T4 turbo at the boost level you are actually at you may have to adjust flow up or down.
With most of the Aqumist kits along with other kits the pump is fixed flow and you need to control the amount of flow by changing the jets. Some of the Aquamist kits are mapped off of fuel injector flow and can vary flow up and down based on the amount of fuel being injected.
You want to make sure you are flowing just the right amount as too little water and you don't get the full effect, too much water and you will bog our engine down (smaller displacement motors are more effected by this).
Water seems to bog the engine down more that water/meth mix.
If IPD has a compressor map or flow numbers for the 4T4 turbo we can do some simple math to figure out where you need to be. Even some data logging that shows us how much lbs/minute air is flowing into the motor will work.
I don't remember the formula off the top of my head, but I will look for it.
If you can figure out the lbs/minute of air flow into the motor, a good rule of thumb is most turbo cars will make 1 hp to 1 lb/min of flow, so if you are flowing 350 lbs/minute you should be close to 350 hp.
If you are running the good washer fluid, it's supposed to be 50 percent distilled water/50 percent methanol, .01 percent blue dye, although the MSDS can tell you for sure some times.
I believe the IPD kit comes with 650 cc injectors, and we have 5 of them.