I'm not convinced by claims that tuning the map to your specific vehicle as a result of test drives could produce anything but marginal gains over an off the shelf remap.
one thing which convinced me is that one well known tuner who uses the custom tune method tuned his map to a car as it was presented to them. The owner was delighted and all was well.
But the car had an underlying swirl valve fault which once it was rectified the remap wasn't as much good and needed to be reworked.
Once I present my car for remapping there are only so many variables. DPF/no DPF, induction kit/standard induction, and so on, so surely an off the shelf map will be good enough. Considering that the standard map from the manufacturer was the same off the shelf map for every single car they made (at least in large batches), what could possibly go wrong ? If the tuner had to do too much to the base map just for my car then I would ask them for a refund and to reload the original map, because there must be something else wrong which might become a major problem if the extra stresses resulting from a remap are unleashed.
If Tom's standard 1.9 JTDm, Dick's and Harry's 1.9JTDm are all taken to the tuner on the same day as mine for a DPF removal and EGR delete, what other variable is there that differs between our cars that require specialist remaping ?
If this was motorsport and every HP means the difference between securing next year's sponsorship and losing it, then I wouldn't expect anything but lots of rolling road testing and live telemetry.
But when we're talking about producing 25%-30% more power by a remap, IE a vague ballpark amount, does 3HP more matter, if that's all we're going to benefit from by extra RR sessions ? I don[t think so...if a tuner says to me that for £150 I can have 188HP with an off the shelf remap, when I currently have 150HP, but if I pay £700 I can have 195HP, I think I'll be telling them to cancel the RR session. And, I think they know that too