I've got about 550 behind the engine, and with four people in the boat, it kicks out a good wake already, especially when the gas tank is full also. When I've had only two people in the boat, I'd added Phat Buddies, one on each side of the engine. It's pushing alot of water then, and it kicks out a good wake then also.
Next time I'm out, I plan on running to Big Bump bladders, one on each side of the engine going back to the back seat. They're 750 lb each, but I think I'll fill them about 2/3 way full, as I think 1500 lb would make it run sluggish.