To yield best sound locate the sub behind the rear seat facing the hatch.  I
use a q-logic 10'' sub enclosure and it is awesome.  Low  nose-tingling bass
from the dual-voice-coil speaker and my 350 watt Bazooka amp.  I can easily
move it to the floor for sleeping. I keep my amp under the driver's seat.

Chris S.
'85 Westy
www.knology.net/~vw/
http://groups.yahoo.com/group/wolfsburg_campers