you can find a LOT of mods for rfactor on rfactorcentral.com
i have rfactor for soe 3 or 4 years, i like it very much, because i can get a mod of almost any car i wan't to drive, and still it is a very good sim, of course you will be better with rfactor 2, but it seems to be with some bugs, for what i have heard, i would like to play rfactor2 but i won't buy it until it comes out, until them i will still play rfactor 1