I do have them on the '55, but I used them more for the reusability rather than any sort of "performance gain". To answer Jerry's question of "why not just use the original oil bath?", mine didn't have the oil bath, but rather the base air cleaner, and it was mssing the original element. It had a very ill fitting paper element in it. I originally wanted to run the oil bath, though, but at the time (this was before I had internet and discovered the Stovebolt), I couldn't find any original oil bath setups. So I went with the K&N, as the housings I did use take an odd size filter. The ability to clean and reuse the K&N appealed to me.
