The goal when developing this Process West top mounted intercooler was to make it the very best aftermarket top mounted intercooler for WRX/STi... period. The guys at Process West studied competitor products and fixed all of the mistakes they have made...some of them were major. The most obvious error that EVERY competitor makes is not supplying their intercooler with proper ducting/shrouding to suit the increased size of the new intercooler. There is no point in installing a larger intercooler and leaving the factory under bonnet splitter/shroud in place. 

The next major problem that we see competitors doing (and they all copy each other) is building an intercooler that is too thick. Their design criteria is spot on for bragging rights whilst marketing. They say that bigger is better. This is totally not the case with an intercooler that is mounted at 90 degrees to the ambient air flow. For good heat exchange to take place you need good ambient airflow through the intercooler. In the case of the boxer engine with its intercooler mounted under a bonnet scoop the ambient airflow speed is already struggling after doing a 90 degree turn through the scoop. The last thing it now needs to do is find its way through 114mm (4.5in) of intercooler core. This will result poor heat exchange and high inlet temps. Our intercooler is 90mm thick (3.5in) and in turn the intercooler breathes, gives lower outlets temps and in turn more power.