zac451 - I can get to my pump fairly easily. It is under the dinette seat. I turned on the pump and opened one of the faucets to a fast drip. Then got close to the pump to see where the noise was coming from. Most of it was from the flexible "pex" tubing vibrating against the wall of the RV. Some small bubble blister packing wrapped in the correct place made it reasonably quiet.
I was going to put in an accumulator tank, but could not figure out an easy way to keep from filling the tank with RV antifreeze when winterizing.