Resurrecting an old post, but for anything looking for new wastegates, we've actually had really good luck with the TurboSmart IWGs with a 2mm preload.
We've had several customers as of late come to us with their wastegates at 100% with only 12 psi due to age and stretch. Replaced with the TS units and back to 15 psi and 67% wgdc in no time.
Just something to think about