Designing Kitchens and Bathrooms - Sound dampening plumbing and new tile floor?

Hello,

We just moved into a home built in 2002 by pulte. It is a two story, with the master bath and bed on the main floor, and upstairs are the other bedrooms and other main bath. The 2nd floor main bath is above the 1st floor master bath.

The 2nd floor bath is a toilet, shower/tub, and two sinks.

When my mom came out to visit for thanksgiving, we noticed that the bathroom noise from the second floor was very loud--it woke us up. Not sure which water noise (toilet, sink, or shower) but I would guess it was the toilet.

There is a linolium floor in the 2nd floor bathroom.

Here is my uneducated inexperienced vision:

Remove linoleum flooring. drill 2" or so holes in subflooring/under sink cabinet and blow in insulation with high sound dampening properties down into areas where the plumbing is (walls and flooring). repair replace holes. Justify the expense of a project that no future home owner will be able to see (hopefully) by replacing linoleum with tile.

That is about all I know.

Can this be done? What kind of insulation? Any dangers?

The problem is PVC drains, the solution would have been for the builder to insulate the pipes when the walls were open. After the fact it gets very difficult. Even if you blow insulation into the pipe runs, it is doubtful you will adequately insulate that space.

Would a better tactic be to knock out the sheet rock on the first floor and address the situation from there ?