I did EXACTLY the same with a Golf GTD, 19's no DCC and only 40mpg.....but, If I put the DCC tyre pressures in (from 35/35 to 42/38) it then did over 50 mpg but crashed around even worse, sold the POS, it was neither a decent diesel or a GTII don't like the sound of that the Rs3 suspension not being comfortable ? I hate crashy suspensions it is the reason I sold my Golf R years back within 4 months as it had 19's and no DCC what an expensive mistake that was .