I already have the forge DV which is only 8 months old (put on by previous owner) but the last few days I have been driving with the windows down and have noticed a fluttering noise when on boost but not when letting off! I'm guessing the issue is with the DV not being able to stay shut under boost or a split hose. I'm doing a few jobs on the car tomorrow so i'll give the DV and boost/vacum hoses a check. I've done a search for flutter but most people seem to have it when letting off not when on boost. Oh and it doesn't do it every time!