I notice that most people have the amp installed in the trunk. Does anyone have one under the passenger seat ? In my old integra I had mine under the driver seat and wondered if that would be possible for the passenger seat in the "S"

 

You'll probably have to use the drivers side seat since there is less room under the passengers side due to the starter hump.
You need to be aware of dimensions and probably limit power to something reasonable so you don't overheat the seat and your butt.
This is also where I'm going to instal my amp.l