Power of a car is not soley dependant on fuel type, but also on the type of engine oil you are using. If your car uses mineral or semi-syn, might as well stick with the RON97 unleaded fuel. But if you filled your car with fully-syn, then its worth trying out V-Power.

But overall, I have tried both the defaul Shell 97 and the V-Power (havent tried the new V-Power Racing), I cant tell much of a difference because I'm using Shell Helix Ultra fully-syn engine oil and most of the time my ignition is smooth and quiet, smooth accelaration, pick-up and power is there, good fuel consumption and perfect idealing. No knocking or what so ever.

So try experimenting with diiferent brands of engine oil and see which suits your best for overall performance. Word of caution, if you have been running on mineral or semi-syn for more than 50,000km, then dont change to fully-syn.