On my Uly I actually run 2 open hoses, fuel lines, one for each cylinder down to the muffler behind the chin fairing. I have absolutely minimal anything come out of these, even when my Uly fell over while on the stand and it was running nothing came out of them, note the kill switch worked. 2 hoses I think give better air flow and it was actually easier under the air cleaner to run 2 hoses rather than T them together. I think better airflow keeps them cleaner, oil under pressure will create oil vapor, opposite of water vapor which is what you want to come out of these lines. If I did add a catch can I would use a steel screen or no filter at all instead of a paper or cloth filter for optimal air flow & less maintenance. Actually stock on the Uly there are 2 lines running into the air box next to the temperature sensor after the air filter and before the throttle body. This mod enables nothing but fresh filtered air going in the air box and over the temp sensor as well as down the throttle body. Cheap to do, less maintenance, better performance, etc... my opinion and experience it is well worth doing
or a catch can so you are not polluting our planet[cool]
