And how long time have you been doing that without issues?

Personally i think the durability and lifespan of the gearbox, has a lot to do with the way the car is driven, but i would like to hear your experience about this.
Maybe i'm totally wrong? I have not covered enough miles in my own car to have any experience with this, but i am aware of the problems i could or should i say will get? when running 400-450 ish on a standard box. So honestly i'm thinking about running with a lower boostpressure until i can afford a decent gearkit upgrade.