I remember seeing this thread last week, because of the comment about the turbo being "turned up." Do you have a manual boost controller on it? You'd have a knob to turn for the boost. That's not something you want to have on your car. It sounds like you have a bad boost leak, and that can be really anywhere. I'd check the bypass valve first, but I'm willing to bet that if the car has a MBC, that they installed a blow-off valve too. Does the car go "pshhhh" when you shift? I'd check there first. Give us some more details about what's been done to the car and we can help. The thing is this: the more details we can have, the better we can help. Mechanics can see what's been done to the car, so they need less of an explanation, but we don't have that benefit. You can always take some under the hood photos and especially around the turbo and intercooler areas. Really, if you take photos, don't worry about how many you take and get as close and as many as you can. You can delete them later, but if we have more detailed shots, we can usually pick out what's been done. Good luck.