I'm not a competitive or club rider, but I am a bit of a gearhead and I love looking for ways to make my gear my own.
In light of that, I'm wondering if any of the posters here are enthusiastic bicycle people who I might be able to talk to about ideas I have for upgrading my Trek 2.3 with new components.
What do you want to do? There's a serious law of diminishing returns in biking. The biggest upgrade you can make is the rider.
Putting more expensive components on that bike isn't a wise investment in my opinion. To upgrade from 105 to Ultegra you're looking at $1000 or so, and the difference is minimal.
New wheels and tires could help, and are easy to transfer to a new bike.
What do you want to accomplish with the upgrades?