Perhaps I see about 10hp diff between hot day (90+) and chilly day (50-) on my N/A Z car. Butt dyno, of course...

Now, on a turbo car, in 50F and with no intercooler you would produce certain amount of HP before detonation.

On same turbo car, without intercooler and in 90F you would produce less HP, due to earlier point of detonation.

With intercooler, 90F weather air is cooled down to, say, 40F air if pressure was 1 atmosphere, so now it feels like non-intercooled turbo in 40F weather. Now you got slightly better HP in 90F, then you did non-intercooled in 50F weather.

With spray, you go further, cooling 90F air to, say, 10F air if pressure was 1 atmosphere, so you gain power as though you were driving your turbo car non-intercooled in 10F weather, but its still 90F weather out there.

Increase the PSI, and differences become more exagerated, up to a certain limit, imposed by the spray/IC/combustion.

Disclaimer: Numbers are just guesses, don't flame me for miscalc, I'm just trying to convey a picture...