just did some calcs in my model.
A 36F (20C) increase in what I call snorkle temps at760cfm is about 9kW of additional heat and results in an increase ex the charger from 170 to 215F (dT 24C) and your AIT's "post charge air cooler" increase upwards from 131F (55C) upwards towards 170F (78C) - so almost 1:1
This drops your density and hence grams/sec and hence due to AFR measured via your MAP drops your fuel input and hence again - drops your horse power.

On a stock 75/157mm 14.5psi setup,Air Intake Density (Plenum) drops from 2.39kg/m3 to 2.21kg/m3
(after alllowing for a 25% improvement in cooling in the charge air cooler due to the greater dT).

This has a direct and almost proportional effect on horsepower of about 7.5% (20hp)
So the relationship between snorkle air and Plenum air is almost 1:1 (due to the cooler working harder 'cause the temps are up). Its just easier to strip heat out of the plenumm air due to the greater dT.

A very rough "rule of thump" corollary to this is that for every 36F (20C) you can nip out of the snorkle air (or for that matter AIT) - you'll get about 20hp extra through increased density going into the cylinders and that equates to about 10kW.

So if you can meth to cool 10kW or KC to cool 10kW - your get about 20hp gains.
Of course at 3000rpm the benefits of the KC improves since it is working regardless of rpm/speed.