I think the primary reason people dont go with the Apex is that the core is really weak. From what I heard, Troy from XS Engineering who primarly cares Apex products said to stay away from that intercooler. I also heard from SP Engineering (Chris) that the core is weak too.
But the Skyline GTR intercooler is not the same as the supra kit. That intercooler is thicker.
Again this is from what i heard but I do trust the people who told me...
you should go with HKS type S if you are only running stock twin and not planning to upgrade turbo in the near future. Its plenty!
even if you decide to go with bigger turbos later, I bet the FMIC can be sold in a day used.
I didnt go with Apex cuz of its lack of pipings. Greddy is the best bang for the buck but still expansive...plus, I have no money to upgrade single in the near future anyway