You can think of an intercooler as a radiator that cools the compressed air (intake charge) that the supercharger pumps into the intake manifold. There may be two types of intercoolers on the market — air-to-air and air-to-water intercoolers but, although air-to-water intercoolers work wonders on extremely short runs and are ideal for drag cars, they are not practical street- and endurance type racing cars. For street- and endurance type racing cars you would need to use an air-to-air intercooler. As with turbocharged cars, an intercooler is not a performance part per se, but it performs a fundamental and important role in a supercharged engine to maintain engine reliability. Its main purpose is to cool the intake charge. Reducing the temperature of the intake charge has two benefits: it makes the intake charge denser and denser air produces more power as it has more air molecules per cubic inch; and it reduces the possibility of detonation. Unfortunately, the intercooler has a major disadvantage: it is an obstacle in the intake charge path and causes a drop in boost pressure! Unfortunately there is no way of getting around this problem and the benefits of having an intercooler far outweighs this disadvantage. The best you can do is to maximize the efficiency of the intercooler and minimize the pressure loss caused by it. You can minimize the pressure loss caused by the intercooler by designing efficient intercooling systems that to keep pressure loss at a minimum. Firstly, you should use a plate-and-shell core rather than an extruder core as the plate-and-shell core offers less resistance to air flow. Secondly, the internal flow area of the core has a major affect pressure loss. Therefore you should select an intercooler with the correct internal flow area in order to keep pressure loss at a minimum. The following graph is a good tool to estimate the required internal flow area based on your supercharger's flow rate.