The Zero/Sports World League Catback exhaust has been designed to meet the highest standards in the Japanese market. In addition to being made of the highest quality materials, it has also attained JASMA recognition. The unique design of this exhaust allows the exhaust noises to be kept to a minimum while allowing maximum Performance and the retention of the trademark Subaru boxer rumble. The loudness of the exhaust never exceeds 92dB and at cruising speeds the exhaust is 70dB while acceleration only increases the level to 78dB. The overall exhaust piping is 70Φ in diameter.