I do Hollister a lot, and I run in a Frontier. Wife took the X, lol.
They are extremely capable, straight stock. You have a bit of an enigma, a 6 speed Pro-4X (Off-road in '09) is in high demand on TheNewX, Xterra Nation and ClubFrontier, etc. (Members from all intermingle across sites, there's a lot of them here too)
Best thing to do for your rig if you're going to be crawling the rocky CA terrain are skids. Engine, gas tank, transfer case. the stock skids are crappy sheet metal and I wish they were my first mod. Hefty Fab and Shrockworks are the go-to's for this. Same for front and rear bumpers and sliders. Again, if you plan on doing real ridgerunning, you *need* these. White Knuckle makes a fabulous set of sliders too, that's what I have.
In the meantime, I'm glad to see you have no stock running boards or mud flaps. Either that or Hollister ate them (happens to all of them eventually!)
Look into the rear differential breather mod. The stock breather is a little inch tall one-way valve that sticks horribly and when your diff heats up and creates pressure, it releases it through your axle seals. You find a barbed fitting (search aforementioned sites for this. Make a username, you're gonna be there a lot) and run tubing from that fitting up into your taillight, to keep water out and allow diff pressure to remain normal.
Last, but most certainly not least, look for signs of SMOD (strawberry milkshake of death)
SMOD occurred in Xterra and Frontiers from 05-10. Basically, there is a small box in the radiator which transmission fluid passes through. This acts as a prewarmer for transmission fluid (opinions vary wildly, some think it cools the trans fluid. I don't know about all that. OEM trans at 150°, engine coolant at 180° who's cooling who?)
Anyway, the seals in this box fail. Badly. Allows trans fluid and engine coolant to mix. Strawberry milkshake in your radiator and horrible transmission failures. Usually results in full replacement of both.
Do your research. SMOD is a truck killer. The prewarmer can be bypassed, so it may have already been done, or you are lucky enough it hasn't failed yet.
Sorry for the novel. I know these trucks fairly well :-) TNX/ClubFrontier has a crew of NorCal/Nevada rock crawlers and ridge runners that do 5-6 outings a year. We are going to Hungry Valley in 2 weeks. You're welcome to join us!!!
http://www.clubfrontier.org/forums/showthread.php?t=253266
I'm known as R00 across those forums :-)