Just had it flashed with APR Stage 1. Seems to want lose power after about 5500. I did put a knock off Forge type Diverter on it. I am running the heaviest spring 18-21lbs and a washer in it. Tuning problem with it? I can here it whistle and it is popping off fine. Pulls very strong now in comparison to stock though.
Is the low end of the Spring Boost Rating its Hold and the High its spike? I need clarification on this. Kinda new to the Turbo stuff. Came from Old school V8's and Stroker Air Cooled Dual Weber 64 VW Bug.

Is 5500 -6000 about it maybe and knocking on the rev limiter at the Redline or the Diverter not holding boost enough up there?

Red 2002 TT 225. APR Stage 1 and Diverter. Going going for Muffler Delete axle back soon.

 

I thought 5500 was a good shift point anyway unless in 5th and 6th gear...but I had my car flashed with gaic a couple years ago and noticed that the psi was dropping significantly after 4500 rpms in 4th gear. I looked into it and ended up replacing most of the silicone hoses for the turbo because they get sucked closed with really high pressure. That happens and no power...

 

someone correct me if im wrong but I believe your turbo is maxed out around 5000, i'll look and see if I can find a boost curve. But tappering off at -5k rpm sounds right. (stock)