I've been running the PSD cold start fix on several different bikes this winter. Soon to be an SF as well, just waiting on the harness. So far the cold start fix has been great. The bikes I install a koso camshaft on typically NEED the cold start fix. The bikes I just do intake/exhaust on I haven't had the need to use the harness. It will help don't get me wrong, but typically a little fine tuning of the air screw and the idle screw (buy a thumb screw idle from steady garage, or F4i cable and cut it down) goes a long way.