Wait, wait... so to go along with rbtree's serious rant... homeboy said that having the second port is like opening up the vent on a gas can. On a gas can, the vent lets air get "sucked back" into the can, so if the port did work as he says (obviously doesn't, gases attempting to go from an area of high pressure to an area of low pressure, no way in hell there's going to be a vacuum on one of the holes and pressure on the other, but let's pretend, and go along with him) then "suck back" is happening with his mufflers. In one of his previous listings for just the cover, he said that stihl made dp covers for the 066, but not the 044/046. I called him out on that, and somewhere in the talk after that, it became apparent he was a member of one or more of these sites, but I have selective amnesia. WTF indeed.