REMARK Y-Pipe Kit. Infiniti Q50 (2014+) / Nissan 370ZY Pipe Kit: RO YPQ5 N 2. 5" to 3. 0" Y Pipe bolts directly to the downpipes. Combine with midpipe kit, and axleback kit for a complete catback exhaust system. Reduce exhaust backpressure to improve performance by allowing the exhaust system to flow more freely. Y pipe includes flex couplers on each leg to reduce stress on the merge collector for long lasting usage. The Y Pipe does NOT eliminate the catalytic converters which are on the downpipes.