i have an 2009 diesel x5 which i have a tuning box on, and i think it has made very little difference in power/torque. i was thinking of getting it mapped but the reason i went for a tuning box was so i could take it off before it went in for warenty/service work so the garage could not detect it. i was speaking to a guy the other day and he said that if i was to get it mapped there would be no way of the garage telling it was chipped.is this true?