I have a M25 that has a 90 degree hose nipple coming off the side of the valve cover. No hose is attached. You can feel a little pressure of air/gas being pushed out while the engine is running. My next door Cat 30 owner's M25 has a hose attached that runs down below the engine. I have seen a picture online of an M25 that has a hose attached that then runs to the top of the air filter. Bought mine used about 22 years ago and it has never had a hose attached. Rebuilt the engine 10 years ago and didn't notice it till a friend pointed it out last week. Is it a breather hose that I need or just leave it as is?