Yeah... you're right. The size of this self powered sub is just a tad too big to conceal under my seat. However, this self powered sub has the capability to power the entire system. My attention was drawn to this setup because you are getting a decent sounding sub without the hassel of hiding two amps under the rear seat with the wires and etc.
If I build a sub under the front seat, I'm not sure how good it will sound. Guess that really depends on making sure I build and enslore that has the right volume for a decent speaker and proper power.
Right now, I have a Sony XM-10020. (300 x 1 RMS) to go with my Sony XM4050 amp. (50 x 4 RMS). Then I going with a one 10" sub, JL 10W3V3-4.
http://mobile.jlaudio.com/products_s...p?series_id=24
I'm not looking for a killer system. Just one that will sound decent. The amps are brand new, never used. But they are from the late 90's. I have had them in storage for about 10 years with the intent to use them.