On my TT it was also bolted to the floor, but it was mounted to a flexible rubber foot. Mine was loud also. I never really bothered with it because we only dry camped about 3 times in 13 years. What I did notice was although the pump was mounted on a flexible mount the water lines were rigid mounted. If I were to quiet it down I would've cut the lines back and looped flexible lines so it didn't transfer vibrations. However i fixed that by buying a class A with the pump mounted down in the storage compartment. Now I can barely hear it,
That was my $65k fix!