Subs seem to have lost power... Why?

[2000BlackCoupe]

i dont feel like wiring up 2awg or 0 . had a hard enough time getting the 4 through the blank hole in the firewall (passenger side). plus the whole big 3, upgraded alternator, deep cycle batteries. too much headache for some bump

but my old 2 12" type r's and hifonics bxi1606d thumped great on 4gauge