Although I consulted the TerryLove website, I simply could not believe that a 1.6 gravity operated toilet could function well without pressure assist. I had a Kohler, ADA 1.6 model that jammed; and even though it was beyond the warranty expiration date, Kohler gave me a refund on it. Out of total frustration, I finally gave-in and bought the Toto Drake model. It has operated FLAWLESSLY, and I strongly recommend it. Ted