I have to ditto the last part of the post above. It's the RIDER not the BIKE. You don't need bar end shifters or aero bars to race. Just because those are popular for tri's does not make them indispensable. Upgrading the wheels won't make you super competitive - better to spend the time training rather than hours researching, upgrading and then retuning your bike. Folks, it may be hard to believe but people raced fast before STI, 3x9, carbon and aero.

I would bet that lighter wheels and aero bars would be lucky to cut your time by a few percentage points - far less than you can do with more training. Once you have learned (and possibly saved) more you will know what you need/like, either in equipment or a better bike.