Update on 4091... Yes it is quieter, everyone has noticed, but I had an AFE megacannon before, so I guess that is not totally out of the ordinary. Before I decided to go ahead and try it out I emailed Amsoil corporate about returning it. Surprise, surprise... no response... but that is what I have come to expect from Amsoil. Great products, no customer service after the purchase (at least at the corporate level, there are alot of reputable dealers out there). Anyhow, back to the filter, I haven't noticed any change in egt's, so even though it is quieter it appears to flow sufficient air. I have the plans ready for the cold air intake, just need to pony up for the Odyssey battery to clear up space on the passenger side. I may make one small change though, dual filters (idea came from Duluth), you can never have too much air.