Anyway, the 2006 VTi shouldn't ping using 91 RON. Tell your dealer the problem. If they say it is normal, get them to print it on the service report that they heard it but it is no problem, so that in the future if anything does happen, you have something to hold against them for not fixing the problem..

BTW, 98 premium for me as it gives slightly better mileage and offsets the 10 cent price premium