The reason that the K&N paper style filters are bad is because they allow particles that are big enough to destroy a nitro engine to pass through. A well oiled foam filter will allow your engine to last A LOT longer. Trust me, I know it looks cool. I have been drag racing and building hot rods for many years, and I'm a huge K&N fan, have one in every vehicle that I own, a lawnmower, and a tractor. But, I had a rude awakening when I got into RC's. After seeing some of the cylinders on engines that had a K&N filter, I was appalled. It's strictly motor saver for me. A lot of times, it only takes a few particles from one good bass session in the dirt to ruin a nitro engine.