I'd like to find out as well. I know that with the stock 6 speaker system you can upgrade to the sub (there's a white connector with a black cap tucked away). And so far it seems I wouldn't have much trouble running the infinity speakers in all corners. I'd imagine however, you'd need to figure a way to bypass the GPS antenna if there is one. Harness is another issue.
On Nissan's, regardless of model they tend to be wired full feature unless it's some ridiculous audio / video package. I'd imagine it's along the same lines but I haven't been able to find a wiring diagram from the factory.
Either way, I'd love to use the factory navi setup, add my own speakers, amps and subs. The bezel throws me off too.
åXS 6K LB / Fog å PLED DRL 6K å NeoTECH TArms å XMB, SR FMB å Whiteline Bushings å iXon and NEFD Lip Kit å H&R Springs