Hello Priuschat! I recently installed a 10" Alpine Type R Subwoofer (Installed Alpine Type R 10" Subwoofer! | PriusChat), but the trunk rattles were annoying and made listening to music less satisfying. I was able to completely remove mine with only FELT pads intended for chairs. Note that i went for sound quality, not overpowering bass on my setup. I am only pushing 20% of the subwoofers' capabilities. First, you have to keep your rear liscence plate from rattling. In order to do this, apply 3 or 5 Felt Pads to the back of the licence plate. One near the top right, one in the top left, one in the top middle. This was sufficient for me. Second, have a look at the inside of the trunk door/lid. You will see a black automotive carpet type pad attached to the inside of the lid. On the inside of this carpet, its hard plastic, and this was the other main source of my rattles. You will see that it is fastened by plastic pins that are secured. Don't take these out. Instead, kind of pry the carpet piece so that you can fit a felt pad onto the top of the carpet piece on the inside.