Hi I have som Pirate Mfg replacement rear vents and I don't just want to start pulling at the rear trim to get it off, if there is a special way to do it - ie unscrew speaker somehow and that makes the rest of the cover come off so I can unscrew vent from the rear? http://www.piratemfg.com/H20015SC_Bi...p/h20015sc.htm Any help would be appreciated.