Originally Posted By: ltslimjim
If I went away from the K&N drop-in filter for my car, should I go with AFE Pro Dry S or AEM drop-in for replacement?
SlimJim- If you want to stay with a reusable filter, the AEM Dryflow does better than the AFE Pro Dry S in filtration tests. The Pro Dry does not do well in filtration efficiency. The AFE staff always recommend their oiled cotton range (AFE ProGuard) vs. the Pro Dry because they claim it is more efficient in filtration, and the tests we saw agree. But it is a pain to deal with re-oiling, and, even then, the AEM Dryflow still scores better than the AFE ProGuard when looking at filtration.
FWIW, you could also use a throwaway OEM filter and be fine. In fact, your filtration efficiency would probably top that of the AEM, and your dust capacity would be higher.
One caveat - fit can make a big difference. These comparisons assume that the fit with your intake is good for all filters, but it's really worth checking when you install the filter. If you don't want to bother with checking fit, then you are probably better off with an OEM filter, which likely will have good fit.