I just purchased the 2013 Sportage EX AWD. The canadian version does not come with the premium sound system like the other versions. I like sound in my car and lets face it the factory system is not good at all. I like a little bit of bass in my car and always install subwoofers, however with this car I want to keep it factory. My question is has anyone been successful in installing an aftermarket subwoofer in the back trunk storage on the right that looks like a storage space. (in the sx it has a sub, ex it is just a hole) Would I need to buy a box for it or would it just mount?