Not according to the schematic that came w/my '06, nor per my dis/re-assembly when installing the RO unit.
I pulled the city water fill out to install a pressure gauge tap, & it is a backflow preventer (basically a neoprene flapper valve in line w/the hose connection) only. No regulator encountered.
Electric pump will keep ~50psi on the line from the tank into the house, but if city pressure is higher, that will control & pump won't add. If city is lower, pump will bring it up to ~50.
Baja-tested '08 2-slide 36'
Alpine: The Ultimate DIY'er Project