An aftermarket downpipe such as Diamond Eye's 3-inch model will improve power, reduce exhaust gas temperatures, and improve turbo response in a Chevy Duramax diesel truck. Installation of this downpipe is easiest with your truck on a lift and can be accomplished with simple hand tools.
Raise your truck on a lift or use a hydraulic jack to raise the truck and place on jack stands. Make sure you have your truck in park with the parking brake engaged. It is possible to install the Diamond Eye downpipe without raising the vehicle, but raising it will give you more space to work.
Remove the driver side plastic fender liner with a 7 mm socket, using a pry tool to pop the liner off the fender. Remove the air box with a Torx bit and use a flathead screwdriver to loosen the clamp. Remove the heat shield covering the rear of the turbo outlet to downpipe assembly by removing the four 10 mm retaining bolts. Remove the retaining clamp that sits along the firewall with a 10 mm socket.
Remove the factory clamp between the exhaust and the factory downpipe. The downpipe is connected to the turbocharger with a V-band clamp. Use a 7/16 socket to remove the V-band clamp, approaching it from outside the frame rail. Remove your transmission dipstick and place it aside; it will interfere with downpipe removal. Remove the downpipe lower retaining bolt that sits right above the connection point to the factory exhaust. Remove the downpipe from below the truck.
Slide your Diamond Eye downpipe up into the space formerly occupied by the original manufacturer's downpipe. Re-use the factory V-band to secure the downpipe to the turbocharger outlet, then connect the downpipe to the factory exhaust with the factory clamp. Attach the Diamond Eye downpipe to the lower downpipe retention bracket by reusing the factory hardware. Reinsert the factory transmission dipstick.
