I use a 50/50 mix of (sented) isopropyl alcohol and hydrogen peroxide to spray down my hockey equipment after games to prevent bacteria growth and keep my equipment from smelling rancid...the reason I mention this is that when I was removing the glue left behind after removing the original sound deadener, my bottle of this mix was nearby/handy so I sprayed the glue and used a razor blade to remove the glue...worked great! I use this mix all the time for different things, but originally it was for my hockey gear...just thought I'd mention that this worked really well for removing the old glue...and the isopropyl alcohol and hydrogen peroxide are cheap...I buy 16 oz. of each and mix in a 32 oz. spray bottle (less than $3 USD)...I typically get the wintergreen scent, but obviously the scent isn't important...but it smells good!