Theres plenty of mods available for the Pathfinder, just depends on where and how you look for it. The Xterra, Frontier, and Pathfinder all pretty much use similar parts so you kinda have to dig for it. Its really all in how much you want to spend. Since CA has strict regulations you may have to pay a little extra to get emission compliant parts. Try searching on other forums for ideas too, don't just limit yourself to a pathfinder specific forum. try
www.newx.org theres alot of good info on there to utilize in your search.