Inject that water into your air intake stream (aft. intercooler) and watch the EGT's fall as well. It probably will reduce EGT's better than just spraying the IC with water..... the guys I have seen spraying their IC with water are doing it because they have very low surface area..... we on the other hand have plenty of surface area.
The air/liquid IC's are great for low pressure drop. Pressure drop is how much you loose across the inlet/outlet of the IC. Since many are cooled by iced water... . the ability to get some really low intake air temps is beneficial. Having yet another setup in my truck that has water/coolant and a pump is not appealing... . the less moving parts, the better.
There are even 'intracoolers' that use the refrigerant from the A/C system and make for intake air temps well below ambient at full boost on a hot day.
Since we are using compression ignition, I would think that intake temps that are too low would result in bad combustion and possibly low power.
Matt
On edit: BTW, Spearco is one of the most respected names in air/air IC's..... their cores are expensive and you usually have to buy the endtanks separately and weld 'em on yourself. Spending $1200+ on an air/air intercooler is not uncommon.