Air to water intercooling is very inefficient.
It has about half the efficiency for the same area because the heat has to be transferred twice.
But the biggest issue is that the fluid is very prone to heat soak turning your intercooler into an interheater. Even the OEMs are not able to solve this issue, you won't either.
Run air to air.
Unfortunately, the layout of the car and stock-looking-car concept does not allow installing a front-mounted air-air intercooler or a like-APR air intercooler in a sandwich (I have genuine APR intercooler from previous project). Therefore, the optimal solution is to use a water cooling system from BMW x6m with a thin intercooler installed in a sandwich and two intercoolers under the hood.
