Just my personal thoughts. I've read a small amount on intercooler design. No expert, just read a bit. But, in general, you are supposed to be better off with more fins that are shorter, than fewer, longer fins. The stock unit, and other aftermarket units have fewer but longer fins. So, that would mean that in theory, it would be better if the fins were turned 90 degrees from the way they are. The duct is like 22 inches long. It should in theory be possible to make an intercooler where the core is something like 21 inches by 6 inches or so. And that would be, at least normally, a much better design.
On the other hand, given the proximity to the engine, the core may benefit from longer fins even at the expense of fewer fins -- this is the compromise that Mazda chose. So, I guess it would take making some prototypes to see.
At any rate, there is only so much that can be done in the TMIC location. Thicknesses that have been tried are 3", 3.25" and 3.5". But, the 3.5" hits the duct. Maybe someone could re-design the duct to increase airflow. But, how much improvement could be made? Thicker is always better, but how much effort is it worth to add an extra 1/4" thickness?
What I'm saying is, I'm not completely certain how much room for improvement is left compared to already available options. If turning it sideways would work, then that is possibly something to try.
That, and, yeah, must have a better cold pipe. I can't believe nobody has come to market with a redesigned cold pipe. The market does NOT need another intercooler if it uses the stock cold pipe.
There was a project that TRZ was considering, where they were going to include a cold pipe, and, if I recall an option for CO2 coils inside of the intercooler. But, they dropped the project. It would be cool if someone would pick that project back up.
EDIT: I see that Corksport has already said they are using stock cold pipe. Oh well.
Someone else mentioned the AutoEXE suction kit. That is an upgraded cold pipe, plus a few pieces like silicone hoses. Its $450 because of the Yen exchange rate. Somebody should make something like it for cheaper.