A few words of advise before you spend some money here:
The Bose subwoofer box has some "unusual" wiring, so you will need
a) either the original Bose amp
b) open the box and re-wire the whole thing (and at this point you can also swap the crappy Bose subwoofers with some good speakers)
c) do it like TriGem2k and invest A LOT of money and re-do the whole headunit/amp/speaker system of your box
But be advised "out of the box" the Bose box will NOT work and even potentially fry your amp!!!
See also:
http://www.renntech.org/forums/index.php?showtopic=11577&st=20
http://986forum.com/forums/showthread.php?t=9349&highlight=bose
I bought a used Bose box, did the needed mods to hook it to a 6-channel (M490 ?) amp from a 996 and IT SOUNDS LIKE CRAP !!!!
It's currently #1 on my "most useless mods on my Boxster" list
