Hydro assist no question.
Even if you don't buy from them, give Lance or Kelvin a call at PSC... I only bought a cylinder and cooler from them, but was told all kinds of good stuff about getting my box and pump to work alright. They still aren't ideal... but that's because I am making do with my stupid Mercedes box on my 03 TJ
Fine off road, it's just twitchy at highway speeds.