Had similar issues with my plumbing system. Eliminated all noise and pulsation by redoing sloppy factory work.
Specifically re routing of most of plumbing in and around the wet compartment. Many of the flexible pipes had crimps from too sharp a bend. Many of the harder pipes were not supported or were rubing(vibrating( against body panels and echoing. I used Home Depot foam pipe insulation and remounted pump to float better and allow lines to be straighter. Pump was hammering because of restricted water flow at the inlet hose.
All is nice and quiet now.
2003 34' Dolphin 5342, W22, UP, UPGBrake, F and R Track Bars, Rear IPD sway bar, Koni FSDs, Safe-T-Plus, Scan Gauge II.. 2004 Jeep Liberty, Blue-Ox Adventa..