I'm with Musky,
You aren't going to get ANY benefit unless you're running 60mph or better, and at those speeds the engine itself is doing a pretty efficient job of sinking heat. The real issue with these engines is in "stop & go" traffic, where the engine overheats because there's not enough air flow. An oil cooler isn't going to improve that at all. Best thing to do, in my opinion, is to listen to your bike and give her a break when she seems to be getting too hot.
Oh, other important note. It's a Yamaha, so just RIDE IT!!!!