S&B CAI-FME-15-1D JLT Cold Air Intake Kit Dry Filter18-21 Mustang EcoBoost 2.3L No Tuning Required SBJLT's 2018 2021 EcoBoost Cold Air Intake is better than ever. Fully computer Designed to optimize space and for best fit and Finish. Large 5 inch filter inlet with radius end for tons of smooth air flow. Turbo end is 2. 25 inch to meet up with the factory turbo, but then it steps up to 4 inch with another barb in the tube. So when you add a bigger turbo all you have to do is cut the end of the tube and add a larger coupler to fit up to a 4 inch Turbo