I started to use castor 927 but I was riding my banshee everyday pretty much all day for about a month on my lake behind my house a couple of weeks ago and the castor was just to expensive to buy everyday. I have been using the 2S (I still am) without fouling any plugs of anything at all. I recently saw the yamalube 2R in the store where I usually buy the 2S. Thats why I asked.
I am running the same set up as you. 2004 Banshee Tr6 with 2:1 filter with outerwear. I run 32:1 yamalube, 280 mains, stock pilots with Toomey needles on the 4th groove just like the instructions say, it should run near perfect if your all stock.