I received the JLD bridge system yesterday and installed it on my Eastman Arch back Flat top Jumbo. This guitar's bridge was slightly separated along the back edge and there was significant bow in the belly. Installing the JLD brought the bridge fully down tight to the top and reduced the belly about 70% right away. The guitar did sound thin and tight when I played it last night but I picked it up this morning and it is already opening up nicely. The JLD is a good system. It works as advertised. I will give a tad more tension to the rod with my next couple of string changes and expect that will reduce the rest of the belly.