FWWIW: In the UK, shower booster pumps are v. common. Typically, they are set on the FFL. and often fixed over a sandwhich of:
1. a rubber mat.
2. a square of ply
3. a rubber mat
4. pre-drilled screwholes
5. plugged with plastic plugs and a shot of silicone.
6. the screws are set with rubber cups.
This will eliminate all, or most, of the washing machine gone wild noise that pumps can generate.
It's not necessary, of course, for Whirlpool's and similar.
I do hope that no one minds me referring to UK practices, it's not to teach anyone to suck eggs, far from it - especially from me, but merely showing a perhaps different way of doing stuff.