The GC8 as ive heard is alot more tolarent to mods. Even though they might be tolerant (less protest), you never know what you are doing to your car's engine.
TBE and a Atmos
BoV i found were ok as the
TBE allows the turbo to breath better and the
BoV is the same as a stock one except it vents into the atmosphere (which aparently is bad as the computer cant analyse the air being released and not being plumbed back).
You have a GD though i think? Id get an
ECU as my first real upgrade if you are going to upgrade things such as turbos. I am currently building my car AROUND my turbo and leaving it till last. Aslong as my mods can withstand a decent psi ill be happy, but an aftermarket PowerFC should allow me to tune it.
So in answer to your question, you can drive it for aslong as it goes. but even though it might not show signs of damage, or funny noises/
ECU protest, doesnt mean it isnt being rooted or leaned out.