The 2.0 is engineered to run on 87 Octane gasoline. If it is pinging, detonating etc and your ignition system is functioning properly then your combustion chamber is so dirty that it now needs high octane fuel to run.
I would suggest running several tanks of LubroMoly Ventil Sauber or simalar product or find a shop that does a high pressure fuel injector and combustion chamber cleaning.