Bad vibration. Help!

3 months ago i started top hear a mental on metal noise as i went over speed bumps and when decelerating below 2500rpm in 2nd and 3rd gear. Now the vibration is severe and loud and is in every gear when decelerating. Gets worse when I turn on the AC and turning off the car also sounds terrible. Think the downpipe hanger is shot? could it be making that much noise? I have an intake, 2867r, charge pipes, depo racing IC, CPE Exhale kit, FSWerks catless downpipe, and MBRP exhaust. like I said, it all started 3 months ago and has only gotten worse. Ideas?