stock turbo efficiency?

[starjet]

what is a stock turbo good for(boost wise) on a stock setup? i think i remember hearing not much over 20psi, but i cannot remember. what are the boost level limits for the stock turbo?

 

[John84GN]

I was running about 22-23 psi.

But I was starting to hear some squeaking noises under boost, so I sent it away to John Craig. He said that now was a good time to get it serviced, so I figured that since he had it, I might as well go w/ the TA-33c upgrade!

By the way, I only had 5,000 miles on the turbo.

John

 

[starjet]

how do you know when you hit the end of the efficiency of a given turbo? do you add more boost and not get more power?