take celtics figures with a pinch of salt, they're a big franchise tuning company, with any big franchise (im sure ill offend some now ) they will have dealers local to you, this could be a spotty teenager that knows nothing but just does the flashing of the ecu and takes a cut
the big franchise because they have many customers all over the place wont necessarily give you a personal experience or a personal map tied to your car
stage 1 is usually on a vehicle that has all oem fitted items, and keeops within the limits of them
stage 2 is usually for a vehicle that either A) likes being pushed to the max on oem items or B) has a couple modification such as better breathing on intake/exhaust this could be a k&n filter and DPF delete
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