Shouldn't be a problem
The wastegate serves two functions. First, it is a mechanical safeguard to prevent over-boosting the engine and causing mechanical damage. Secondly, it is there to vent excess heated gasses to prevent spinning the turbo out of it's efficiency range. And causing turbo damage, and engine damage from excess heat.
As for will it shorten it's life? It could. If you're over-boosting it constantly. In a KW that could happen. But in our Cummins (at least in our application), it's probably not gonna happen. There are guys that run that turbo at 30-35 psi all day long and have had no ill results. Much higher than that, and you will probably damage it.
Does that help?