Ppl are giving you advice you're asking for... now are you actually taking it in?

In any case you would want to have a seperate tank for ur i/c water spray and water injection. One need methanol, the other doesn't. Dual windscreen washer bottle in the engine bay will suffice for water spray and boot mounted (min) 10L tank for the water injection.

RMS prob the most experienced at doing the water injection so that and i/c spray can be sorted there.

Unichip go Slakos, its in Ozzy park but u should be more concerned about how long u can drive ur car after the tune than how long it takes to get to the tune.