I've installed a new shower and am getting horrible pressure, I can use it to shower but it would take hours to fill up the tub (it was fine before this installation). The sink in the bathroom gets normal pressure. I've removed the showerhead and there isn't anything clogged (bad pressure even with the head removed). I've removed the faucet (diverter valve is attached to it) and I get bad pressure out of the faucet pipe. I've replaced the mixing cartridge in the shower handle and it doesn't have any affect. When I remove the cartridge and turn on the water to the house, I get a great spray out of the rough-in valve. I've even run bailing wire through the pipes up to the showerhead and down to the faucet to check for obstacles - none were found. I keep thinking it must be the cartridge but am running out of ideas. Does anyone have any suggestions? Thank you.