Let the fuel go down to almost zero and filled up with the Shell expensive stuff, feel the difference almost straight away, still running mine in 523 miles on the clock and give it some beans now and then, so many Golf GTI /R on the road and nobody knows that mines a special one, bit frustrating as i dont get a flash of appreciation unlike driving the Focus RS 500, and Escort Cossie, but thats exactly why i bought it for my daily driver.