Planning on running two SA-15s probably off something like this http://www.sonicelec...-BK1300.1D.html in the back of a 2000 ford focus wagon. Would subs like these require an alternator upgrade or would they run fine off stock, and also if SA reccomends a 3.0-4.0 ft^3 @ 35hz ported box for one sa-15; around what size do you think two of these would require? And would a box that big fit in the back of a ford focus? Any help and suggestions on things I havent asked here are also appreciated !