Thanks Carbon! yes, the billet diverter valve is a recirculating valve and that should be taking care of the issue of the sudden back-pressures that have nowhere to go except back to the compressor housing, causing friction to the blades etc. It's interesting how a project like this, where the original idea was just to replace the turbo, snowballs because of all the interdependencies etc. And as for the recirculating valve, absolutely necessary since I don't want any damage to the new turbo because of some back-pressure issue resulting for example from an abrupt closing of the throttle.
And you are absolutely right about the professional help. The last thing I want to do is spend all this money for all these parts and then screw it up because I wasn't skilled enough to do the job properly. That is why I have decided to let CARR Industries do the job. There is a very multi-talented individual who knows these cars inside and out and is the perfect person to do the turbo/headers/wastegate - job. And also the Boost control and the diverting valve as well as the valve covers.
But you also hit the nail on the head with the statement about me wanting to experiencie this job myself. Absolutely true. This is half of being the Porsche enthusiast to know exactly what is where and how it functions and what is involved in installing a specific piece or fixing it. That's just as exciting as the driving part.
But fortunately I have now done enough myself to get a feel of what it really means to get some bolts that are stuck loose without breaking anything and so forth. I also know enough about doing the rest of the job that I could do it if I was OK with taking a very long time doing it. And I am a bit impatient. Rather let someone who is used to doing it do it quick and then let me enjoy it. In this case it will be good enough for me to just know how its done.