You can boost only as much as it will let you if it's completely stock. You wont get much if there's no intake or exhaust mods on the car. Otherwise, it's like the turbo is sufficating. I think max lbs. of boost you can get out of a s4 TII completely stock, is 14 lbs. ( I could be wrong, but that's what I've been told). So turning it up all the way won't make much difference, until you get those mods on your car. Even then, I wouldn't boost over 14 lbs. unless your motors built to handle it. Or you will chunk out a seal.
