Upgrade the wheelset, crankset, brakes, shirters, handlebars, seatpost, headset, pedals, the frame...and you will be good to go......it should not cost you more than $1500....and you will get a very light bike for riding around the park....

just kidding....

if you love the bike...why change? I know "upgrade" is an infectious word in bike forums or any bike circles. thats somewhat keeps the industry going. and highly effective marketing teams with thousands of dollars are doing a good job of making us feel inadequate. so, the moment you get a bike, you feel like you need to change things..you need to upgrade....while certain upgrades are necessary for comfort or performance, I would argue that most upgrades are overly costly and unnecessary. and they dont make real deference in performance.

Now, there are a few things that may make your ride a bit more comfortable......like a riser bar, saddle of your preference, a set of ergonomic grips - lock on grips make a huge difference in installlation and removal, pedals....and sometimes, tires - tires that suit your riding style and terrain......

you can do most of these changes yourself.....but, for the rest of the bike, I would change or upgrade as things break or wear out.

now, ride your bike and have fun. pay attention to your bike and your body and they will tell you what to change.