the R&R is weird.
Here is my car with a boost up, running only cat back and .8 bar. and it didnt seem to hit any sort of "hole" in the revs (small flatten off though present, but nothing like i have seen on some)
After a while at this boost it now does have a massive hole, you can feel it when driving. The flatten off it major and the second kick feels like its hit boost again. But i cant remember it being there when it was first boosted.
Judging on this thread, maybe the way to make your turbo last at this boost is to treat em mean and keep em keen