Just thinking about fitting a K&N cone filter on the 250 which would allow me to fabricate a volume box for the exhaust in the space freed up and then doing away with any need for an end pipe. Just a thought at the moment but really not sure how the K&N will affect the running so any objective ideas welcome!

My experience with K&N filters is that they pass more air to the point where you will probably have to re-jet.

Cheap horsepower.

Be careful if its wet being cotton they do not flow air.

I prefer foam such as ram air which self drains if wet.

In any event the further away from splashes the better.