Man,.....I would run the outerwears. Save and get them,...its better to have more protection for your carbs. There is alot of crap that can get sucked down a carb than what we see and are told of. K&N is a great Filter and I'm pleased with mine. I feel the filter does a great job, but a prefilter adds another layer beside a filter for dirt to have to go through...thats a plus with me!! I want the cleanest air for my shee that I can get. I want my shee to last a long time. If the outerwear is dirty or dusty; it only takes a few minutes to wipe or wash them off and install them before you store it till the next ride. If you dont have an airbox lid that fits over your airbox before you wash it, use a plastic small bag with no holes and wrap it over the sides and back of the airbox the best you can. This will keep you from filling your airbox with water during washing. (High Pressure washes use a large rubber band or something to keep the bag from flying off). After washing remove the plastic bag carefully to one side and let water on top drain off. wipe the airbox out and store. Its nice to take time and have your quad ready to pull out for the next ripping trip. If your riding everyday, just wipe the pre-filter off with a clean rag before you go out. Its just good maintanance.