you are going to get many different opinions, and that's because ppl race in different areas of the world and have different dirt and track conditions. Being in the air filter business I've attempted to test in every kind of dust you could imagine. the dirt in your pic looks to be very fine dust which is why if you didnt oil the outer it looks clean. the fine particles pass through the pre-filter clogging the inner. In my opinion, dust should never reach your inner filter, unless your in a super dusty condition (like what your pic looks like) and run a more open cell outer oiled and the dirt gets trapped inside the outer instead of on the outer surface like my filters do. for regular dust conditions using my filters or like mine work great, but when you get into the dust like in your pics you have 1 of 2 options in my opinion w/o effecting engine performance. 1 you run both oiled and change every run, or 2 you run a more open cell outer oiled and run it til the dirt just hits the inner. #2 is the best way for performance but it hard to make ppl understand letting dirt pass into the filter in the correct thing to do. its called a "pre filter" for a reason. offering different outers is something we may do in the future. look at MX filters, their inners and outers are never the same material. the outter is always bigger pore so the surface doesn't clog. idc what ppl say about vet wrap, its a bad idea. ive tested it on a flow bench.