Lower pressure ratio means less heating but don't be fooled into thinking it won't detonate. If the cylinder is getting filled nearly completely detonation is more likely to occur with the same timing. Reducing pressure drop at the inlet, runnjng in better ambient conditions, reducing pressure drop across the charge air cooler, increasing charge air cooler surface area, using better cooling like ice water instead of air, reducing compressor inlet temperature, running correct compressor housing, correct compressor, higher CR, correct cam and cam timing can all reduce charge air temps. Some indirectly. Getting a higher mass in the cylinder on the intake stroke across as much rpm span as possible is more important than anything when trying to make power. You have trade offs. Running the engine at a higher rpm can increase mass flow a lot without adding manifold pressure. Getting a combo that does that is easier said than done.