Alot of the 16vers owners run premium due to the knocking of the piston which is when fuel is burnt either a cleanly or roughly one the big bangs can cause a knocking in the chamber which is why a knock sensor is on the 8vers to retard timing when its got stock fuel. On a 16ver you have no luxury of a knock sensor its usually all go which is why the head is more suited toward 99 Ron. Some people run advance timing all the time and sticking 99ron gives better performance, but if you stick 95 it runs badly.
You can retard the timing to run 95, but all that does is save the head from premature wear. TBF a 16ver is always going to drink fuel, but its a fools gold to think 95 is cheaper and you will get less efficiency from the block which uses more fuel in the long run. Most people will only run 95 for short periods if you can't get 99 stuff in an emergency but over time you can hear the engine knocking under load due to inferior octane levels. Either advance the dizzy or not but choose one or the other for better fuel consumptions and saving engine wear!
