General Motors replaced their well known, durable CP3 injection pump for the CP4 injection pump. GM also went from traditional fuel injectors to piezo fuel injectors that require less fuel. The new injectors proved to be efficient, but the CP4 pump didn't. The new injection pump wasn't durable, and it couldn't keep up with stock Duramax, let alone a modified one.
We offer aftermarket injectors from FASS, XDP, and Pureflow that will increase the longevity of the CP4 injection pump. You will notice an increase in power and fuel mileage, especially if you pick up a quality tuner that will optimize the new system; properly fueling your Duramax. As long as you properly support the CP4 pump, you will be pleased with the results. However, we also offer conversion kits if you'd like to replace the CP4 pump with the old reliable CP3.