I've been running K&N Air Filter on my 01' since I bought it last April. No complaints and no problems with anything getting past filter. Since I was changing to Amsoil synthetic oil, I thought I'd try their foam dual stage filter. The filter itself look great, however placing it in the stock air box makes me nervous. There seems to be no surface on the air box "hinged" side to hold the filter in place. This seems to cause the filter to possibly gap and allow contanimants to get by. Unlike the K&Ns, there is no hard surface to hold the configuration of the foam filter. Unless, someone can tell me what I'm doing wrong, or how this filter will stay in place, its history. I'll go back to the K&N. The oil, oil filter, and fuel filter will stay, but there's no chance I'll gamble with something that is not ridged enough and will allow dirt to pass. I'm looking for you guys that have been using the Amsoil filters to tell me what I'm doing wrong.