i thought this was one of the trusted main tuners
thier website promised greatness
celtic "authorised distributor" done my last c class( circa 60k miles so not an old shagger) stage1 , i can verify it drove great as advertised but had an intermittent boost cut fault which was a pain, probably on threshold of map sensor or something but they did not want to know or honour any warranty they claim on website.
would rather try hold your car to randsome getting it in at a labour rate to test for a spurious that could take ages to pin point. Then at risk of them blaming a part on your car.
wouldnt even put back to standard for free.
they didnt have a dyno and i had to go a walk for 4 hours till my car was ready, so think they send your file to main body or run table amplifier type algorithm . as i wasnt allowed to see what they done i can only speculate but would never use them again as their word is null
had to go to another tuner