I have owned a 400P for several years. We used to camp on the beach and air down the truck and trailer tires to 15 PSI. This little guy really gets the job done! What's nice is not just the max PSI, but the high CFM rating, which is what you need to fill a tire fast. My truck tires are pretty big, 265/75-16E that need to go to 80 psi.
Downside is that it draws just under 30 amps, and it comes with battery clamps on its power lead. I wired in a trolling motor plug on the bumper of the truck that I can just plug it into.