when i ordered my HMF exhaust.. it came with a K&N filter and a pre filter..the prefilter wraps around the K&N and keeps any small dust and such from getting through..i know of many people running the K&N with the pre filter for years without any trouble..as for as not having the noise if you order the HMF pipe also ask for the quite core..only 20.00 more and almost as quite as your stock pipe,.,