Will Changing Registration Details Alter My Rankings
The contact detailed you provide when registering a domain name are used by quite a few sites and search engines. For example websites that provide a domain lookup service usually return contact details which would of be obtained from your registrar, the same goes with google as well.
Quite a lot of what you do to your website can affect the way it ranks, if you change servers that can have an impact depending on where the new server is located. Server locations can have an impact on your search engine position as the server location gives google an idea of what country hosts your website and will rank your website higher in the results page for that country. Obviously your domain extension will play apart as well for example a .com domain will rank better than a .fr in google.com but a .fr might rank better that a .com in google.fr.
When it comes to changing contact details and registrars google will not penalise you as it knows that chaning address or registrar is part of life and every domain name may have its details changed several times throughout its life.