What rockford amp? 2000 watts peak or rms. t2000 RF is underrated gives about 2400 watts rms...
isn't 2000 watts excessive for an L7?
figure you're stock alt output and stock bat output then the the amperage on the rockford. (30-50 amps should be left to run car?). If you're close in giving the amp what it need then second batt or capacitor will do.
Second alternator is best solution to servere under powering though...