one thing u'll learn quick fast is that modding an R20 with high end stuff can quickly start adding up. sticking with a downtube/dahon will provide a very comparable package right-out-of-the-box.. so take a look.

another thing with the R20 is the time spent looking for parts and installing them... its a lot of fun, but can sometimes take up more than you expect!

make sure you get fenders on ur bike as ur first mod, should they not come with any.