I am trying to install some quality 6x9s (MB Quart) in the old 4x10 slots. I was wondering if anybody has tried the speaker adapters? If they mute the sound any? If they don't sound good, I am going to try and cut and create some kinda of mounting surface in the back to install the speakers. I have heard of cutting the space that is over the backseat arm rest to mount 6x9s. Any comments or suggestions?