That is a hard answer to quantify without seeing the whole picture.
Peak power is a very narrow metric for looking at overall power production or driveability. Just because a car makes more peak HP does not mean I would consider it tuned. For example, you can bolt on an exhaust or an intake on these cars and because boost is a function of airflow over the MAF sensor, this car will make more or the same peak power, as a car that is tuned running an AccessPORT. The reason being is that the untuned car is running more boost, however, there is no control over that boost, it just does what it does. That goes for timing changes, fueling changes and boost control. The tuned car, will probably have more area underneath the power curve, more consistent boost control, more consistent fueling/AFR and appropriate timing.
The other thing to consider is you have no way of looking at knock correction etc. Looking SOLEY at power production is a rather myopic way of looking at tuning. Sure, you can have some impressive numbers on the dyno, but if the car is running dangerously lean with uncontrollable fueling and boost, it won't be running for long.
Tuning is the key.