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			I'm not sure the specific size - but having just done a hunt this past summer for a sub - I can tell you there aren't a lot of options out there that fit cleanly without some major modifications - or footwell loss.
 I ended up with a self-powered Kenwood that fits very nicely under the passenger seat without any trouble.  I have an upgraded head unit and no amp, so was a very simple set up.
 
 If you have the bose MOST system, might be more complicated than a simple plug/play kenwood sub.
 
				__________________2011 Boxster 987.2  Arctic silver / Black leather, PDK with Sports Chrono Package Plus
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