Not relevant to the TFSI or K04 but....
All good fun and something we spent many an hour road mapping/altering/adjusting on my old Saab 9-3 Aero coupe project, I had the stock TD04-15T unit with the Forge Actuator and 2.3 conversion which managed 300bhp and 350 LB/FT and ran a 5.5 second 60-100MPH in 4th gear. Tried both the Green and Yellow springs both with and without addition pre-tension and did a run whilst logging and made adjustments etc.
You reach the point of clutching at straws especially if you cannot custom Map or alter the duty cycle of the boost control solenoid.....Adding another turn on the actuator can alter the base boost by a few PSI which throws out the rest of the software this causing an aggresive boost built or spike. Too little pre-tension and the Airmass request cant be achieved. Balancing act indeed!
I would probably advise anyone against making any actuator adjustments on their cars without proper mapping or logging equipment, just my two penneth :)
Cheers