Originally Posted by Adam-M

See your original question wasn't quite as clear as that Glenn, Tesco 99 and shell v power have the same octane raiting so you can use either, but bp is only 97ron so you can't use it if mapped on 99.

I've seen a test done before where Tesco made a minuscule more amount of power and torque than v power so it much be good, my dad ran it for years on his Impreza and that got abused.