Hello, My house is 4 years old. I bought it new. Three bathrooms, 2 on second floor, 1 on first floor. . The toilet on the first floor doesn't flush that well. I don't know if the reason is because of venting, or if the reason is because its a 'builders' fixture (Mansfield is the brand). . Would replacing this fixture with a high-grade model from Toto make a big difference? . Here are the symptoms...Flushing the toilet seems to fill the bowl, which raises the water level in the bowl, there is a small delay, then a flush which is not very powerful. Water pressure in my area is not great. There is no clog in the pipe. . I can do the replacement, just not sure if I should. It would only be less than $300.00 to do the job. Thanks for your time.