The thing I don't understand is Ron 95 is supposed to have a higher octane rating than the previous discontinued standard pump gas (Ron 92). Would it be conceivable that problems happened with a switch from 92 to 95 ? Doesn't make sense.
I personally have not found any problems with Shell Ron 95 in my Hyundai Coupe, although I have not really tested their 97. So perhaps on the next refill, I will put in 97.
To be frank, not one opinion in this thread is backed by any form of testing with scientific methodology. So it's pretty hard to draw any firm conclusions whether there really is a problem or just someone's vivid imagination (the 'Placebo' effect....look it up if you don't know what it means).
For the timebeing, I'll keep my opinion regarding 95 to myself, although common sense would normally dictate that if you run a performance car, you really ought to go for the fuel with the highest octane rating anyway, which in this case would be 97.