Keep one thing in mind. You car will always do given speed in given rpm. That is how the gearbox work. If my punto is doing 100 @ 2500 rpm then your will also do the same. What has to change is the time to reach that speeds. Straight away ask them to put a replacement turbo and check. Also as i said earlier check the actual boost vs desired boost readings. Its as simple as that and can be done in 5 minutes.