I'd like to add to Oldheads comments about intercooler design. There are many complex objectives and compromises that must be balanced when designing or choosing a TMIC. Some manufacturers simply cram the largest core into the available space and don't give sufficient thought to airflow around and through the core. To get this part of the design right you need to consider the the entire aerodynamic situation at the front of the car. Air flows across pressure gradients which don't necessarily flow from front to back and an air scoop wont flow any air unless there is a corresponding outlet.
I was involved in development of the Hyperflow TMIC and at one point in the development a significant decision was made to reduce the size of the core because we found a larger core simply blocked the exit path for the ducted airflow, so while the bigger core had less pressure drop internally, it had poor cooling. We also found the larger core had more thermal inertia which means that it would take longer to become heat soaked, but when it did it would take longer to cool down. For a street car a slightly smaller core made more sense.
Another thing to consider is the internal design. Cheap intercoolers use extruded tubes which have a lot less surface area for exchanging heat compared to finned tubes. Hyperflow use the best quality tubes which are sourced from the US because they're not available from anywhere else.
In a nutshell, you get what you pay for.