DESCRIPTION The Banks 25999 Boost Tube Upgrade Kit is engineered to improve airflow and enhance the drivability in your 2017-2019 GM 6.6L Duramax L5P. By utilizing the industry's largest diameter tubing, this Boost Tube Upgrade Kit improves throttle responsiveness and decreases turbo lag. Banks Boost Tubes are manufactured of high-quality aluminized steel and improve boost pressure retention. This results in increased air density between the turbo, intercooler, and intake, resulting in increased horsepower. The Banks 25999 Boost Tube Upgrade Kit boasts an 87% increase in flow over factory tube as they feature 3.5" mandrel bent tubes that dwarf the stock 2.5" crush-bent tubes. By using a unique billet aluminum cold-side adapter and proprietary high-strength 5-ply silicone couplers that work with the stock Duramax intake elbow and intercooler, these tubes further increase airflow. Less boost pressure loss is achieved thanks to a better-flowing intercooler tube and a unique billet intercooler cold side adapter, enabling more air to be supplied to your engine.