mate it all depends on the condition of the turbo, at 22psi it wont last that long if the turbos standard, but then depends on how much right foot you give it , as soon as you turn up any standard turbo thay dont last long, best bet is to get one built for the spec you wont as in hybrid, this is what i did i spoke to ian howells and told him i wanted to 17psi on a -34 set up he put together a t3 stage 1 hybrid and its been great , b4 that i turned up the standard t3 and it dident last very long, if you think ford set it to run 5 to 7 psi and say a turbo only has about 75000 miles if its not turned up , so as soon as you turn the boost up the life of the turbo will shorten!
my s2 has done over 115000 miles and im on my 3rd turbo..
but my wifes frst is standard only runs fords 5 to 7 psi and the impeller is perferct its done 73000 but never been abused so that tell you something

andy