Ditto on the DI placement, ALWAYS vertical or, in time, you might as well not even use it. One thing, I'm not a great fan of PPs in public areas. Some are quieter than others, but all make noise. The better ones, with better installation, are pretty whisper quiet. If you find that it is noisy, find a foam mousepad or two and use them in between the pump and wherever it's mounted. The hammer usually isn't too bad, but it is usually evident, so you really do want to take your time and make sure your fitting connections are soild and clean and neat.