Didn't see any posts regarding the topic, although I thought I would post my two cents anyways. 2011 Silverado LT Ext Cab, aftermarket Sony double-DIN head unit. Wanted to install a sub as well as aftermarket speakers, but I didn't know where I was going to put the Amplifier seeing as how there's no real flat surface to screw it into. Solution? The rear passenger seat was the perfect spot for a bit of plywood to be attached underneath the pipe outline for the seat, with the cushion off. I started with a 3'x3' piece of plywood from Home Depot. With the seat in the upright position and the cushion cushion OFF (unhook the two plastic snap clips, one on the back rear of the seat, the other on the inside area, between the other seat), I took the plywood board, and holding it 1" from the bottom pipe drew an outline of the pipe seating and cut out the template with a gerber saw. I used some double sided tape on the bottom of the piping to keep the vibrations down, and a ton of Zip ties to make sure that sucker goes nowhere. The holes for the zipties are drilled about 1" from the edge of the board. You don't want the plywood to go all the way to the edge of the piping near the bottom of the seat (when upright), this will make the fit too tight to reapply the plastic snap locks on the back and side of the seat when putting the cushion back on. Now, BEFORE you put the cushion back on, you have two options. You can predrill the holes for the amp which will make re-finding those holes difficult when the seat cushion is on, OR you can finish installing the cushion and just hand tighten the screws into the particle board. I did the second method, because I wanted the screws tight in the plywood (and it makes it easier to mount regarding the floor space) Below is the finished product.