well you will be spending two times the ampunt of money and you will void your warranty on the sub. JL is not the best priced company out there and not the smartest but they know what there subs can and cant take and they are not rated to take a 1000/1 plus they bench closer to 1500 or so dont they? think a sub rated at 500wrms should be given three times it rated power? Im sure it will work and be loud I just dont think that sub will last long.
You could buy a Phoenix gold xenon 600.1 or 1200.1 and set the gains on them accordingly and they would work also, same technology as teh jl amps, 1-4 ohms running 600 watts rms