Well, it's not *just* the insulation that accounts for quietness on the high-end Bosch units. Some, for example, use friction-less induction pumps to minimize noise, though I am not sure if these units have already made it across the pond. Anyway, my best suggestion would be to get to Bosch's eShop for spare parts. Look up two models numbers - your dishwasher and a 39dB model - and enter them into the search matrix on that site. Look where sound insulation was added on the quiet model - some is actually put inside the pump system. You can actually order the original sound insulation pads from Bosch but most like it's gonna be expensive.
One word of caution: don't insulate the entire tub because you want some area to be exposed to ambient air for the condensation drying process.
Alex
Here is a link that might be useful: Bosch eShop Home
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