I have a 98 avalon xls and I got the same problem most people posting about this had and that is the rear deck subwoofer rattles at just nominal volume with any music that has strong bass like jazz or r&b. Its not the rear deck or any loose fittings, its the speaker (8" woofer or subwoofer). It is made by a company called harmon motive. I wan't to replace it, I know its 4 ohm but I have no Idea what the frequency range is for that speaker. Think the company only does oem audio equipment for cars. Unable to find any info on the speaker. Has anyone already replaced the speaker? If so what did you use and how difficult was it to replace. Don't want to add a box in the trunk but I might have too. Any other Ideas are also appreciated thanks.