The Westcoast filter is a clever design that works if you are looking to keep the stock cover. However: it doesn't flow any better than stock and will require oiling rather than tapping or air cleaning. The MaxFlow for the 500 flows significantly more CFM than a new stock filter, meaning it will run much longer between cleanings. The drawback to maximum flow is that it requires a larger custom fit cover. It also requires oiling when you clean, but since it is larger, you don't need to do it nearly as often. Muffler mods are not necessary with the MaxFLow filter, in fact any aftermarket front muffler plate will reduce the mid-range power that you gain with a MaxFlow filter (slightly enlarging the outlet port won't hurt) Your ears will thank staying stock too. The MS500i is a great saw.