I remodeled the bathroom and put a single handle avalon price pfister faucet in. I also put in a eljer titan toilet. When I flushed the toilet I would get three loud rattles behind the shower valve. I cut holes in the wall, everything was secured down well. I put a water hammer arrestor in the cold line which changed nothing. I have isolated the sound to the shower valve itself. I changed the cartridge and the sound changed form a loud rattle to a less loud thump. Anything else I can do or is the cartridge in the valve to blame. Would a water hammer arrestor on the hot line have any impact? Any other thoughts.