The biggest problem with air to air is the restriction and pressure drop. Some of the drop is the ideal gas law: when you cool a gas, density increases and pressure drops (PV=NRT). Another drop is caused by restriction due to pushing air through long, narrow intercooler fins. That restriction is probably bad for the ST because our core has a long path that air must be pushed through. Air to water intercoolers can improve on that because the thermal capacity of water is high which allows for a much smaller core which means a shorter path for the air and less restriction. The down side is you have to pump water through a heat exchanger to cool the system and the weight is higher than air to air. So far the aftermarket options we have are thicker core air to air but still a long (slightly less) restrictive path. Looking at a generic air-water intercooler (350 hp rating) with a nice heat exchanger and Bosch Cobra pump, it looks like going air to water might cost less than $600 which is competitive with the thick core air to air upgrades. For an intercooler which might be more effective with less pressure drop, I'm considering it. Packaging is a consideration but I'm optimistic. The heat exchanger seems to be the right size with inlet and outlet on the same side, small water hoses and 90° fittings should make the plumbing easy. All I need to do is figure out a place for the intercooler core and the revised, much shorter boost pipes. So far it seems promising if it can fit but maybe I'm missing something. Let me know.