Your tool should not change the status of information coming back from the server because you don't want to see it. This is an education issue for the consumers of your performance testing data, or you could simply build a custom report from the test data which does not include 401 data. There are many ways to generate this custom report, from the custom reporting features/templates in Analysis, to an export and modification of the report of web page. Heck, you might even use a combination of template, auto output of a web page and then SED to modify the page source for the 401 to change it to "401 - expected authentication challenge for application x" in your reporting, or you could just update the value of the 200's and remove the line for 401. I personally would never consider such a path and would go down the education path with the consumers of the data, but that is your choice.