They didn't do any on the outer panel, just the inner part, and they put a ton so its real hard if not almost impossible to fit some mlv over and get the panels back on. I will give that another go before i take everything off, or attempt it, but the cargo door we did and around the wheel wells sound alot better (more dense) when you knock them then the doors.
I see. I thought you were pulling off tiles from the outer skin. If there are none there it will sound tinny.
Try a heat gun to remove a layer or two. (You need to get it over 150 degrees, maybe hotter) It's going to be really messy and painfully hot so wear some mechanics or leather gloves that you never want to use again. Or finds an area where the temps are sub 0. May come off that way as well.