i dont know what type of heat exchanger your using, air-air or air-water. Depending on the duty type your using the car for (DD, Toy) you might think of swapping to a Air-water with a deticated resivoir in the trunk. My truck has a 8gallon resivoir and with ice water at 30-40* my IAT only go up to 70-80* by the end of a run. After a pass my water temp is around 50* and all the ice is metlted. when i go play on the street i usually need to drain and fill every hour and half the water temp can be around 90-110* depending on how hard and long i stay in it.

Granted you may not need a tank so big or replace the water so often on the street, im pushing alot of air with a 66mm over a 94mm turbos and 80psi.