A 63mm outside diameter alloy bend, equivalent to the familiar 2 1/2 inch size and probably the most widely used diameter in intercooler fabrication. It gives good flow for the majority of turbocharged road and club-level competition builds while still packaging sensibly in a standard engine bay, and couplers, clamps and matching components are easy to source in this size. Cut the bend where you need it, deburr the ends, and join with silicone couplers and clamps. Allow enough parallel length at each end for the coupler to seat fully, use good quality clamps at boost, and support the finished run on brackets.