jager, When I made mine I slqanted everything so the oil could run bqack into the engine. I also put a piece of fine stainless screen about 1/3 of the way up in the box to act as an oil seperator. I made a 1' ID breather that fit into the engine without a reed valve, 1" hose, used the stock breather with valve in the box's exit with a small K&N filter. It works fine, very little oil residue under the tail with about 5K miles on it. 12.3/1 compression , 907cc's