You can get away with it on the mk4, the car understeers alot from factory anyway so a rear arb will do wonders in getting it closer to balanced.
I've got front upper strut brace, front lower strut brace, standard front arb (1.6 one fitted), rear upper strut brace and rear eibach arb. I don't get any oversteer, still got plenty of grip only more tidy around the corners.