I replaced the slow rolling Kenda Kwest tires with faster, higher pressure Primo Comets - HUGE DIFFERENCE.
I already had a 1.5 Comet left over from my Flatland BMX bike so all I needed was to get another. If you guys are looking to upgrade your tires,
www.flatlandfuel.com has Comets for $23.99 (the cheapest place I've found).
Pat over at FLF is a stand up guy and runs a tight ship. Super fast shipping and great service.
Right now I'm waiting for my brake shifters and I just ordered a cheap FSA Vero 53/39 double crankset. Even though the FSA crankset isn't the best, it beats out the pot metal stock cranks currently on there. Also, even though the 42T is nice, the 39T will really climb walls when necessary.
The Origin 8 velo seat made a gigantic difference in comfort. I'm so happy to get rid of that gel "comfort" seat. It won't be bad for an upright seated bike, but for a bike with road geometry and drops - no way.