Stutter under heavy accelerate in heat

So I've got a 2007 saab 9-3 with 150,000 miles purchased about a year ago, when i got a stage one tune the car began stuttering whenever the turbo red lines, particularly once the car is warmed up. When its cold there's no stuttering and it gets amazing power. I've changed coils, plugs, ignition module, solenoid, can't seem to find the problem. The turbo doesnt quite sound right whenever the stuttering begins. Could it be an issue with the tune pushing the turbo too hard? I was told its pushing 260hp and 280ft lbs of torque and the car is completely stock. Any advice would be greatly appreciated!

could be an air leak, TB failure, MAF, or any valve related to turbo air circuit or a wastegate rod seized also a clogged cat might be too,if you have an access to a tech II or a complete scanner system bosch or delphi you can refine your symptoms. it's usually hard to find what's wrong with those kind of issues.