Unless you've got something totally new, there are no filters or regulators installed on new HL trailers. But, as mentioned, having a quality, adjustable regulator (with pressure gage) is most desireable. Water filtration, particularly a dual canister system, is also something to consider. But, if you have low volume/pressure and don't have anything connected inline, then look at the screens and reducers in the plumbing fixtures for debris and restrictions. Some of the reducers are nothing more than a plastic disc with pin holes in it.