I've been using an oiled cotton cone filter. I have no idea if it allows more power. BUT, I've been getting my oil tested by Blackstone after the last few races. I've consistently had silica detected, which means dust is getting in and past the rings. The silica number has also varied from race to race which suggests to me that I am not consistently cleaning and oiling the filter or that environmental conditions are overwhelming the oiled filter.
Before the next race I'm going back to paper filters. Of course I removed and tossed my old air cleaner housing loooong ago so I expected that I would need a new air filter housing. I've improved the flow of the engine bit by bit and I didn't want to go back to the stock filter box and filter. That would be too easy. So I was searching around for a filter box from a car with at least 150 stock hp that would work. My son pointed out that his sn95 mustang uses paper cone filters, and the same filters are used for the v6 and v8. Those filters should allow way more airflow than my 2.2L i4 will ever need, so I'm going to rejigger my current intake to fit the mustang cone filters and just replace them every race. I'm not sure that a filter housing is even needed. The good filters, Wix and Purolator, are about $11 on rockauto and the cheapest are under $5.
https://www.google.com/search?q=sn95+m … r+wix&