RENNtech Carbon Fiber Airbox | M177 | 4.0L V8 BiTurboPerformance testing shows that the OEM air boxes on the M177 V8 Bi Turbo engine become a constraint when power output is increased through performance ECU software, exhaust, and turbo upgrades. RENNtech M177 Carbon Fiber Airboxes solve this problem through increased volume and airflow. Substantially larger than stock and a symmetrical design that delivers over 30% more filter area allows the engine to perform at the highest level in both stock and