The TC10165G by FASS Fuel Systems is a very beneficial upgrade for your 6.6L Duramax engine, this is because your Duramax doesn’t come with a factory lift pump like other diesels. This requires your CP3 injection pump to pull your fuel under a vacuum, adding additional stress to your CP3 Pump and risk introduce additional air into your fuel. This is where a Titanium FASS Fuel Pump comes in to help.