Well im big into trail riding i ever do hairscrambels and some other woods races in Ohio and PA. Which is basicly all mud and rock and hills.
The fisrth thing i would say is protrection. Get full Skids that was my first up. Also get some type of nerf bars because if your riding in ruts you get smacked around a lot and done want to run your foot over, i recomend the prm sidebars but if you dont like those they have the same thing but in nerfs just not on there website yet.
http://prm-atv.com/
Second i would say is bottom end all you want is tork. If you plan on not doing any engine work get a pipe, jet it, and air filter that will give you a good boost. I recomend the hmf sport series there all for bottom end and are loud as ****. Also do sone gear raciosr on your spocits. Look at the gearing chart on this website for what to do.
For the tiers ide say go with these
they are called pure sport realtors i think they are the best tier for a sport bike for mud. They have about and inch of tred when new and you can flip them for mud or sand. There 6 ply so there hard to pop and they are not that expensive. They are hard to find and come in 22/12/? if forget wat size i have but they are so wide that you barily ever get caught in regular ruts from other wheelers just way to wide to fit in and they look bad ass.
O if you can try to get some cind of shocks they will give you better conering if you get the right cind and they just make it such a smoother ride. I have works AT Steelers set up for woods for a 180 pound rider and i can barily notice im riding a warrior it feals like a polaris in the woods.
If you have any more questions just ask.
Also im selling a-arm skids becuase i just bought extended a-arms and never got to install the guards i got but they are made by armodillo off road and are still in the bag not opend yet. They are $65 on there webcite but i want to sell them for $50. If your interested just ask and ill get you pics.