Since the walls are new you have a full menu of options for sound proofing. On the pipes I would apply accoustic foam or a sound blocking vinyl barrier. Can be held in place with foam adhesive.
Another product that would work well are insulating blankets and foams (often foil wrapped). This is available in the HI store insulation dept.
Also Homasote manufactures an acoustic wall board (http://www.homasote.com/) that could do the trick.
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