I have a MK2 i-Shift and have only driven on normal petrol until summer of 2016, I was driving on a long journey and so have a go at Shell V-Power. Wow! The car is so much powerful and holds at a certain gear before changing to a higher gear thereby giving more power. Also a small notice of about 2 miles extra per tank. If you join the Shell Club, you get a voucher every 4 months and it pays back the extra costs. I have never gone back to standard petrol unless I can't find a Shell nearby. I have also used Tesco premium petrol and find it good as well and the extra few pence, definitely worth it. My pupils, I am driving instructor, noticed when I filled with standard petrol. So it's not just me being sensitive!
Try it and see how it goes! Have fun.