I've been messing with a 2188 for two years now and still have not been able out cut our 1680 (because of the engine). I'm now considering going into the pump again and putting a torque capsule in. If you have the Cummins engine and it's set right, you have plenty of power. The 2388 might have some really nice features, but if your 1680's are reliable, I think you can update them and save some money. I like the AFX rotor suggestion.