This maybe CA models only but out here the WR's came from the factory super choked up, you can ditch the smog stuff (they sell an AIS removal kit), pull the TINY restrictor out of the stock muffler (or get a slip on), rejet it, and you will have a whole new bike that will feel like a monster! I worked at a yami shop for years and rode several demo WR's setup like this. If you want to take it a step further, find some take-off YZ450F stock cams (pre 2010) and slap them in there...another nice bump in power for cheap!
That bike is a ton of fun, have put lots of time on them in the desert and on the trails, I will keep my modded big bore YZ250F for the track though...cant wait till I can have both! I also have a WR250X supermoto for the street...super fun but I almost built your bike into a full sumo because I really wanted a 450...just getting a legit plate in cali is a nightmare, and the maintanence would have been way more too