Other footwell, pull the carpet back on the bit on the inside of the front wing/fender, where the outside of your accelerator foot would be.
Its a silver box about the size of a VHS video tape. If you look up you will see a smaller black box which is the Bridge Can unit and the smaller blue box (about the size of 20 cigarettes) is the Key code/locking/imobiliser system (I think)
For information only K; the two grey metal boxes you have uncovered there are the working parts of the tracker unit, follow the wires back and you will discover the location of the (often) troublesome backup battery that when it fails WILL drain and kill you main battery. If your insurers don't need it you may want to consider removing it....