I am talking about the external oil cooler that mounts under the radiator, which most racers use. On Gen 4 the engine braking controlled by idle adjustment, you right about that. on Gen 5 a bit different, you are right about idle but in Gen 5 the idle control solenoid controls that RPM adjustment. so it can be set for the bike to idle and for engine braking, on woolich we have a map for it, unlike the Gen4 which it just was an idle adjustment.The bike comes standard with an oil cooler. My bike idles for long enough to warm up and I think the higher idle changes how the engine brake works.