I have had nitrous on a VG30de. I know it isnt turbo or an rb25, but i thought my input could help.
Even a 50 shot at launch will give you a massive increase in exhaust gas flow. This will make your turbo spool a lot earlier, now depending on what sort of tyres you run that can either be a good or bad thng.
If you do go for nos i would use it to get off the line spraying in first and not much else.
Or go for a pressure switch set at say 10psi and have the pressure switch turn off the nos at anything over 10psi.
I am not sure of the kit you are talking about but you will also need a purge system, bottle heater, and decent wiring, distrabution block for your solanoids.
Nos can be a lot of fun at the track but in the wrong hands it will destroy your motor.
and also be careful where you buy it from. whoever sells it needs a proper system to decanter it or you will be paying $100 for a bottle of air!!!