This deals with 10 C6 Z06s. One for a baseline is stock and no tune.
The number after the name is the model year the Z06 was

All 10 were OBD-II testrun recorded when totally stock and all output about the same HP and TQ numbers.
After tuning each Z06 was road tested by their owner and scanner recorded to see the differences.

As seen Z06 to left of graph is the stock one and the 2 far ones, one had CAM and a CAI while the far right Z06 had a supercharger.

MAC09 had a CAI and our water/meth kit and you notice it did as good as Rob's that had a CAI and long tube headers at a much higher cost.

Shown is what each gained
The average HP and Tq gains from tune alone and average gain over totally stock

Note : these are not the best each could do as it only measured how much engine load each driver did in that testrun and does not factor in weather

Here is how the 10 C6 Z06s performed in a drag race via the model/simulator software.

Everything from drivers weight to weather was the same for all except for the HP and Tq each with the above findings.

Six tests, check what each test was at the top of each results sheet.