Durso's will allways make some noise but ya if pipe is to small, it will make more noise.
I will never do another tank unless it's Herbie style. In fact, Combine them for 3 drains. 1 Herbie gate valved, another Durso, full open to take the excess the gate valved one doesn't and a Emergency line.
I want to change my tank now, but I can't get behind it to re-plumb my drains
