That's funny because I have recently turned my box up from setting 6 to setting 7 and mine does the same thing when you put the pedal to the metal it holds back an it is almost like it misfires and after 2 days of turning it up I had and engine light come on saying turbo pressure sensor fault and I had to get the AA out to sort it out and it is the second time it has happend on setting 7 so it is back on setting six can you help me Daron. Cheers