There's always a debate on whether or not to power your 1ohm stable amp @ the lowest ohms for the best output, but under your current setup of one 10", you might hear a difference in quality wired at 4ohms in your coupe. Not to mention your amp will run happiest under a 4 ohm load. However, this doesn't discount your amp's capability, so I'd suggest getting another 10" powerbass, finding a prefab ported box closest matched to your subwoofer's manual, wire them at 2ohms then rock and roll. It all depends how loud you want things, what hip/hop/rap artist you listen to and how well the rest of your speaker setup handles the other frequencies. Sometimes, and most of the time for the regular joe, bigger and louder isn't always better. What's your goal?