Banks Power 17-19 Chevy/GMC 2500HD/3500HD Diesel 6.6L Boost Tube Upgrade Kit - RedBanks massive 3. 5 in boost tubes are the largest charge air cooler pipes on the market, flowing 680 CFM and 87% more air than stock! Smooth mandrel bent tubes deliver more air to your engine while reducing boost pressure loss resulting in quicker turbo spool and more power. Banks Boost Tubes are the largest charge air cooler pipes in the industry measuring in at a full 3. 5 inches. Every other competitive product on the market tops out at 3. 0