On a gravity flush toilet, the incoming water pressure doesn't make any diference in the flushing performance, it will only slow the refill. A pressure assist toilet might be affected if your incoming presure is really low. Don't confuse pressure with volume. If you have old galvanized piping, your volume could be poor, but the pressure may be fine. That being said, a pressure assist toilet will typically be a lot louder than a gravity flush. The Drake is a fine toilet...I put two of them in my mother's house. one ADA height and one standard elongated. Probably should have gotten her two ADA height, but the one that gets used most is ADA.