S80 manual boost controller?

Hi guys! It's my first time on the Volvo forms so bare with me.

I'm looking at a 2003 S80 T6 and I thought, with the twin turbos, CVVT ect. It should be a fun car, and I could get a dual stage boost controller and have even more fun. But I've read on here a bit and I see lots of threads about overboost codes effectively "turning off" the turbos. And some threads saying increasing power/boost <3000 rpm will spin rods?? Does anyone know of these threads have any merit? And how can I increase boost without being denied my turbos?

Thanks!