R4 Sequential Gearbox | Subaru STI - KAPS Závodní převodovky It looks like R4 can use sequential gearbox, which is interesting. I'm sure one will come out for the Evo.
It is not allowed. See page 26 specific regulations: http://argent.fia.com/web/fia-public.nsf/864DF82E9559C3BBC125784D005F574B/$FILE/260%20(11-12)-080311.pdf