The bike seems pretty solidly spec'ed, so I don't see a lot of places to make a big difference cheaply.

Tires are always a good upgrade IMO. Getting the best tires for your given application is totally worth ~$150 in my book.

The fork and shock are both Fox's "performance" level models. I am sure they are pretty good, but there is better stuff out there.... but it is not cheap.

Personally, if that were my bike and I had some money burning a hole in my pocket, I would be looking at tires (if it still has the stock Nobby Nics.... not bad, just not my thing) and looking into getting a PUSH tune/damper mod on the fork and maybe the shock... but that is getting into a few hundred bucks.

For now, just ride it!