We choose an Airflow Systems oil cooler that we were told would give us better oil cooling and lighter weight. We chose the model 2007X oil cooler on the advice of the owner of Airflow Systems. This cooler was somewhat smaller than we probably would have selected (e.g., a Niagra) but he advised us that with a proper feed from the right front of the cowl and through 4" SCAT into a 45-degree. plenum, we should have less drag and more efficient cooling. The problematic part of this choice was that Airflow Systems did not have a computer-designed, 45-degree plenum we could buy for this cooler. Much later we paid Zach Chase to design and build a beautiful plenum from carbon fiber. We'll see about the cooling performance once we fly.