I thought it maybe very helpful because I would be taking it back to them and insisting they find why is it so low down on power, it is not a well car for some reason and a professional tuning company should be able to tell you why
If I had a car dyno low on power then pay a sum of cash for a full service and then dyno again and loose 26BHP I would expect them to already have the reason why it had lost over 10% power
It could be a leak, poor intercooler or something more serious, but the answer should come from the tuner, thats what you pay them for right ??