This is our 4.00 in. replacement Turbo Downpipe to eliminate the often crimped and restrictive OEM 3.50 in. turbo downpipe on all 1999-2003 Ford F-Series trucks with 7.3L Powerstroke engine. Constructed from large 4.00 in. mandrel-bent 16 gauge aluminized steel tubing for unrestricted flow, our downpipe is a must for anyone wanting to make more power with their 7.3L Powerstroke engine. This direct-fit downpipe bolts onto the turbocharger flange using the V-Band connection. Benefits include improved power and torque as well as throttle response and overall fuel mileage.