People have made their own basic kit and then used some Aquamist components. The better DIY kits use a good 100 psi pump. As you found out, its best to invest in a good pump from the start. Beware that different pumps tolerate different mixes of water and alcohol (or other fuels). Learn what your pump can handle if you are using it to flow something other than that for which it was intended. Contact the manufacturer.
Check the Aquamist parts list for the IID, which I think is the model with the high speed valve. I have not kept up on all the parts, since I got my system a couple of years ago. You may need only the high speed valve and the FIA2 injector driver to have flow follow that of the injectors, with a boost onset threshold. You then use nozzle size to alter max flow, so you might still need to verify your nozzle flow and you might need to obtain additional nozzles. More experimentation is required when you DIY. Once you go to the high speed valve, you might as well just use Aquamist nozzles since you will be using that size tube from the valve.
On
www.turboford.org , there may be some info in the archives or elsewhere on making your own water injection. I know at least one person there built a nice system using the Aquamist high speed valve.
Philip Bradley