How much of a difference does the water spray on the type R/RA actually make??
Can you feel a difference in power after a good dowsing?
Does it give a similar pull to that of NOS or maybe a second turbo?
How often do people use it?

 

No chance! It's just to help cool the intercooler, under normal on-off boost driving probably makes no difference, it should help cool the core by a few degrees if it gets saturated though (prolonged hard driving or heat soak due to sitting in traffic with a hot engine).

 

so are we saying that the water spray is pretty usless for everyday driving?

 

Yup more or less. I hardly ever use it these days anyway..