Under seat subwoofer position

Afternoon all, 

Needed a little more bass for my Octavia Mk1, managed to find a small active underseat sub for cheap (Blaupunkt).

The bass response is 'ok' for what it is, adds some depth to the lacking sound in the Octavia Mk1 - now my question...

Where can I mount it for better sound? Or won't it make any difference realistically?

It doesn't fit under seat, due to the design of the Mk1. But have chucked it in the space for original CD changer. (Used velcro on the rear for now and a piece of string to secure - it works!)

Pics below.

Any advice would help, cheers!