I have a tendency to usually get very immersed in my hobbies. I love to mod and spend money. What's interesting with cycling though is it's such an expansive sport that it feels like a black hole of modifications and custom builds.

In the end though I bought a bike for fitness/commuting, and though I want to go faster and further, for me more than a mechanical limit I think reducing my mid section (I probably need to lose more in weight than my bike weighs) and working on my strength, endurance, and technique can do so much more from me than a new hub, crank, or carbon frame.