zsz2k, The high speed valve of the 2d will pulse at the same rate as the fuel injector. You then select a nozzle size that gives the best performance. The will be not need to tune it differently most of the time. If you wish to run the water injection on its own map the 2s is the kit to use with a MAP sensor.
If you want you can use a 2c with a third party ecu.
My best advise is a 2d.
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Brad
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