I want a stealthy sub sound, and am considering the boxes that somebody on here designed so that the seatas can still be fully reclined
(triangle shape).However, I can get hold of 2 std subs for the boxes and the amp that goes into the seatbelt cowling
(passenger). Question is, how will it sound (aftermarket 47wx4 kenwood head unit), and how easy will it be to connect into my non premium sound system, if I use the 300w amp to power the front speakers? 
Thanks guys