For more details see the Search Pro extension page.
To setup the extension, go to Admin Panel → System → Configuration → Search Pro
Search Type - You can select search type you prefer.
Enable Redirect from 404 to Search Results - Enable feature to redirect customers from 404 Not found pages to the search results pages.
Use this section to specify the most important attributes and define search priority for them.
For the autocomplete window you can specify the following parameters:
Also you can choose colors used for design elements of the autocomplete window, such as: