Not suggesting your cooler is a cheapy at all. I have an airtec one too. Just saying that It doesn't have to be the biggest cooler you can fit, it just needs to be efficient.
If you look at spec-r coolers that zetec sam is on about the pipe work is positioned not to cause any or very little "eddies" and force the air to the entire cooler core. Eddies are like whirlpools of air that is turbulent and goes nowhere, spec r have placed their pipework in places to reduces these mis guided current flows.
I may be wrong but I studied it at tech many years ago