I currently use a 1688 and draper head in high yielding rice (200+ @ 12 to 17%). I set my combine(rotor speed, concave, & sieves) to achieve an acceptable loss and set my grain loss monitor to reflect such. My ground speed is usually limited by grain loss (rotor loss being greatest) not by rotor or engine load. Speeds usually are in the range of 1.5 to 2.0 mph. If a 2388 has the same seperating and cleaning area as the 1688 why would I expect an increase in capacity? Where / how does this occur? If anyone has first hand knowledge please explain. Will be trading before the 08 crop to something larger. I need all the input I can get.