Using this 3 - inch stainless steel downpipe is straightforward. First, remove the old, crushed oval - shaped stock down - pipe from your 2001 - 2004 GM vehicle with an LB7 6.6L Duramax engine. Then, install the new down - pipe from PPE. It comes as a kit, so all the necessary parts are included. Remember to handle the woven titanium insulating sleeve carefully during installation as it helps reduce engine bay temperatures. When it comes to maintenance, regularly check the down - pipe for any signs of damage or corrosion. Since it's made of 304 stainless steel, it's quite durable, but a little care goes a long way. This down - pipe is emissions - legal in all 50 states, so you don't have to worry about running into trouble during inspections.