Here's a link to a How-To/DIY guide detailing how to improve the performance and sound quality of the Bose subwoofer on the 2nd Generation CX-9. This should also be applicable to the 2nd Generation CX-5.
www.mazdas247.com
DIY - 2nd Generation CX-9: Bose subwoofer improvement
This is a DIY guide that details how to reduce the "muddy" bass from the Bose subwoofer mounted in the spare tire. This fix has been done by many others on this forum (originally jgriffter, followed by PTguy, jmeitz, Zoom49, greggmischenko, and others). I recently did the same mod, and I just...