You should put the year and model of your car.
But if you have a pass through in the middle I have seen people hook an amp to the inner plastic piece and have it face the trunk using bolts on there to hold it on. so it's easy access to your amp settings.
That's only if your amp is small enough to fit on that piece though.
Otherwise the most common place is on the back of the box.
I'm sure if you searched around enough in the audio section you could find plenty of people's set ups and where they placed the amps, especially the "post up your audio equipment" thread.
