You would hope that the thicker the core the better the cooler?

If you wanted to improve a cooler I think you can get a fabricator to weld wings on to it to scoop the air in and not let the air rush around the sides of he cooler, in effect sealing it to the front of the car.

The Airtec is a good cooler, just not up to the standard of £1000+ coolers like the spec R one which has the benefit of the scoop plus is shorter (lower height) and therefore leaves more air to flow in to the radiator / and or air filter.