are you saying that the K&N one has the bypass valve and the ryco doesnt? iv only ever user rycos on mine, but after hearing that...hmmm
FYI, still using castrol edge 10W60 in mine, now with lucas oil stabiliser
yeah they are a stock thing, also needed for a RWC too so yeah. mine came with them, less than 24 hours and id pulled them off
good idea to keep them handy tho