I have an oem 914-6 oil cooler on my 3.2 engine. I'm planning to put an aux cooler in the front similar to a GT car. GT hard lines, thermostat, shroud, ect.
Air Cooled Racing sells an oil cooler bypass plate that fits on the engine in place of the stock cooler. I would then increase the size of the front cooler since it would be the only one.
The single cooler set up is what's used on the 964(3.6-911) engine as well as Joe's 914-6rs and SirAndy's car.
Any downside?