How about TC audio? i hear they have some good subs as for Fi my buddy has a 15 and it slams but i prefer the 15mag that si makes over the fi any day! actualy check this out
15" STERO INTEGRITY MAG D2 - (eBay.ca item 140310956258 end time 05-Apr-09 14:13:48 EDT)
pretty good deal for a loud ass sub man! i heard ppl getting like 151 db plus out of these subs so jsut think what 2 of them can do! lol!