I have a dual 2 ohm 15'' Fi BL Fully Loaded (2000 watts). And the amp i have is a Rockford Fosgate Prime R1000-1D the specs are (4 ohms 500 watts x 1 chan. & 2 ohms 1000 watts x 1 chan). And i have the sub wired like the pic below. Is the sub receiving the full 1000 watts? And i plan on upgrading to a 1500 watt amp how big of a difference will this amp make compared to the 1000 watt amp?