Using AMPscript to retrieve content from CloudPages

For cloud pages you have to pass the accepted encoding

var targetSite = "https://pub.s7.exacttarget.com/f42z3hbhzzzz"
var result = HTTP.Get(targetSite,['Accept-Encoding'],['gzip, deflate, sdch, br']);

var targetSite = "https://pub.s7.exacttarget.com/f42z3hbhzzzz"
var result = HTTP.Post(targetSite,'text/html','test',['Accept-Encoding','x-request-id'],['gzip, deflate, sdch, br','cp']);

This seemed to work best for me, adding on to what @sforce had provided:

<script runat="server">
  Platform.Load("core","1");

  var url = "http://PAGEID";
  var headerNames = ["Accept-Encoding"];
  var headerValues = ["gzip, deflate, sdch, br"];
  var response = HTTP.Get(url, headerNames, headerValues);

  Write(response.Content);
</script>