Header pipe question.

My LS1 came out of a Vette and included were two steel pipes that attach to the stock headers.
What were these for? and do I need them?

I take it you are talking about the EGR setup. You can either run it which adds complication, or get rid of it and get it disabled in the ECU.

If it went from the exhaust manifold to the intake it would be the EGR (Exhaust Gas Recirculation) tubes. All they do is dump some of the exhaust gas back into the intake. They added it because it burns more of the fuel (not all of the fuel is burnt the first time through). If you don't have to go through an inspection to get your car registered I would take the whole system off. It will keep your intake much cleaner.

You could also be taking about the smog pump. This is a device that pumps air into the exhaust tubes to help burn off all of the unburnt fuel. Problem is it takes work to drive the pump, and that is work your paying for and don't get at the wheels.

You can still pass emissions without EGR. Our cars did not have EGR to start and if you are just trying to pass a sniffer test, removing EGR and making sure you have a cat in the exhaust system should suffice. The only reason I would want to run an EGR is if I had to meet some crazy impossible regulation like CARB in California.

Thanks guys, no I do not intend to run EGR and it has been programmed out of the ECU. Thanks.

Yes, you can just remove it, it will make for a cleaner install. And EGR isnt to burn unburnt fuel, the cats take care of that ( in a factory car). It uses the inert gases basically to take up space in the cylinders, less air and less fuel means your combustion temps go down, it typically only runs at low load cruise.

Mark