I too would like the URL you list added to the Splunk Add-On for New Relic. Note, though, that this URL is NOT raw data. It is Metrics data that is summarized in intervals no less than 1 minute. Raw data can be pulled using the New Relic Query Language (NRQL) which is supported by this TA. This data may be more difficult to work with, depending on your goals. It can be used by creating a new "New Relic Insights" input and entering a NRQL Select statement.