Unlike a supercharger, the exhaust pressure is pretty high at all times with a turbo when boosting.
When I made 50psi boost, I saw 90 psi drive pressure (pressure in exhaust, pre-turbo). A given compressor wheel likes a "correct" size turbine to match for the displacement and target boost. Think of the turbine as a motor; it need X amount of power to make your booast. Turbos have a range of exhaust housings (cheap) that you can use to fine tune and adjust RPM with. Bigger housings numerically reduce drive pressure and move the RPM up at the expense of low RPM performance and width of powerband. Bigger housings make narrow powerbands as a percent of the RPM range. So a .90 A/R exhaust housing might make 75% of max power for 33% of your RPM range, yet a 1.15 housing will only make 75% max power for 25%.
But it has been almost 30 years since I turbocharged a bike engine. I play with high boost diesel engines which are different. Life begins at 45psi. But when I turbo'd a 650 Kaw (30psi), I ran stock cams and springs, and spun the engine 3,000 over factory redline with no valve train damage.
Something I should have noted is that if you get piston erosion, the aluminum will become aluminum oxide crystals and coat the exhaust valve. Feels like sandpaper grit. It is something that can happen at high boost. High spring rates will help the engine run a little longer before the valves seize in their guides and bad things happen.