Underseat Subwoofer

I was in a Freeway Car Audio store last week and was asking for advice on how to get more bass but not have a sub that would take up my entire boot.
I was recommended to get an under seat powered subwoofer and was shown a Focal ibus20. The unit looks pretty sweet and price is within budget but after looking around in my car, I have no idea where I would place it.

I've checked below the front passenger seat and it definitely wont fit and my back seats already has a amp mounted to the back of it.

I was wondering if anyone has tried putting one of these in their euro and if so, where.

The other thing is that I have replaced my 6x9's with Boston Acoustics SR95's.
Looking at the specs of these, they cover the frequency of 35Hz-20kHz where as the ibus20 covers 45Hz-150Hz. Am I going to even notice that this sub is there?

edit: forgot dimensions: (71.5mm x 344mm x 250mm)

Dimensions would help