decorative Chinese 100$ Intercoolers kits:

it looks like brick ...
Garrett truck core:
JDM Greddy Type V-Type core


And in bottom is pictures of top product ARC good example of what to expect from excellent IC core, how much is bigger surface on which air is traveling and cooling and difference in flow obstruction.

So our recommendation is for budget project use Garrett truck core(it's cheap and very effective) and for "real" projects buy something quality.