Product Description Developed on our Dyno and tested extensively on the water, this water box features radiused exhaust tubes and end caps for optimum exhaust flow. Unique exhaust baffle will increase the low-end power and mid-range pull of your Yamaha watercraft. Delivers up to 15hp on modified engines along with significant torque gains. High-strength aluminum construction will survive backfires and meltdowns. Powder coated to prevent corrosion. A must for modified motors.