gistfile1.js

// ==UserScript==
// @name           OutputzGraphNicer
// @namespace      hayamiz
// @include        http://outputz.com/*
// ==/UserScript==

(function(){
  var ret = document.evaluate("//img[contains(@src,'cht=p3')]", document, null, 7, null);
  for(i=0;i < ret.snapshotLength;i++){
    var graph = ret.snapshotItem(i);
    var start = graph.src.indexOf("?");
    graph.src = "http://unicus.ddo.jp/outputz-plot.cgi" + graph.src.substring(start, graph.src.length);
  }
})()