Never had any issues on my old tuned VR6 and ex's Revo'd 280hp Edition 30 Golf mk5 on Tesco 99. Always low Cf (knock correction factors)

VPower isn't always great....

Long story short, guy was racing a Seat ex touring car at Silverstone Birkett 6hr race recently.
On way to testing on the Friday filled up his cans with Vpower, got to circuit, car wouldn't run, lots of diagnosing,fault finding, parts swapping, then someone realised it had DIESEL in it. They sorted that, then when they ran the car the next day the oil had been diluted with trying to run it on diesel - and shagged the engine (hand built Seat-Sport of Spain job)

So naturally pissed off, they went back to the Shell station on the way home they'd used to see if they could make any sense of it, used a different pump or whatever. They went into the shop and started to ask questions, the guy behind the kiosk handed them a card to contact Shell as it was their mistake, the Vpower tanks had been filled with diesel!