Horsepower increases when the intake air charge temperature is cool. An intercooler is designed to cool the compressed air from the turbocharger before it hits the intake manifold. Pressure drop across intercoolers will reduce the effectiveness of the turbo. When choosing an intercooler look for low pressure drop (1.5 psi would be acceptable) and high efficiency. Front mounted intercoolers typically get more fresh air and can offer larger cooling surface area. Careful mounting is required for an FMIC so that the radiator receives adequate airflow.
The HKS intercoolers mount in the stock location. Actual performance numbers are not known at this time. A hard pipe kit is also available to replace the soft upper intercooler piping.
The Alamo intercooler kit replaces the stock intercoolers in the same location and boasts vastly increased cooling capability. Hard numbers are not available however. The kit adds roughly 20 pounds to the weight of the car. It includes an oil relocation kit to mount the oil cooler at the front of the car where it can get proper airflow.
Front mount intercoolers can provide large improvements in cooling due primarily to their location and size. Care must be taken to assure proper airflow across the radiator. FMIC kits are not readily available but can be fabricated from various cores.
This is an old hot-rodder's trick which is usually used to stave off detonation. However, it also has excellent benefits in a turbocharged application in drastically reducing IAT (intake air temperature) and also reducing or eliminating knock. Kits are available from Spearco, AquaMist and Bowling Green Customs. Choose a kit that has a durable and reliable pump, a good variety of different sized nozzles, is pressurized and has a check valve to eliminate pressure loss through the water injection system and is boost adjustable.
Water has a higher specific heat than alcohol and therefore has the ability to offer better cooling. Alcohol burns in the combustion chamber, however, and also mixes with water. A water/alcohol mix will typically allow a cleaner burn.