[hydrashok]

I also feel you should go in for another 601.1 instead of getting a new 1201.1

Like Navin said, the entire wiring in the car will also need to be changed if you get the 1201.1. The wiring upgrade will be less costly if you add a 601.1. More wires, yes, but less costly and, I feel, better (dedicated power wires for each amp).