No water injection system is recommended pre turbo.
These guys recommend it a lot it seems.
http://www.alcohol-injection.com/water-injection-parts-3/Typical increase in boost pressure w/pre turbo nozzle is 1-2 psi increase.
They also say w/there pre turbo nozzles,the water/meth will evaporate as soon as it hits the compressor wheel.
MBHD
