Hmm, I've never heard of Green Filters before. My only concern with aftermarket oiled filters is taking out the MAF. I've seen it happen a few times being an auto tech. Are there any high performance filters that don't use oil?
I ran the Green Filter in my Focus ST for almost a year before going to my CP-E intake. The reason for using oil, is because there is more flow, so there has to be a way to catch dirt/ micro particles. I've heard of over oiling a high flow filter. If you have never heard of Green Filter, get used to the name.. It is by far a better filter than K&N. Don't be fooled.
I never got it DYNO'ed with just the G Filter. It opened up the intake sound. And it is the filter almost all companies supply with their Kits. Cobb being one of them. There must be something to it if COBB supplies the filter with their kits.
Paper filters trap more bits than oiled panel filters...and there is little difference in performance...but with oil changes at 3k and a regular maintenance of re-oiling, I would say it's a wash as far as performance