At first I was pretty disappointed with this vacuum pump. It struggled to achieve the same vacuum as my old 1/3hp pump. But one of the previous reviews on this page pointed me in the right direction: the outlet filter is much too restrictive. Removing it (the cap that houses it can be opened by undoing one Philips screw) fixed everything, and now I can achieve 50-100 micron vacuum instead of the 400 microns that my 1/3hp pump was limited to. I've observed no ill effects from running without any filter, but I'm sure it's a warranty killer.