Invidia | 60MM Test Pipes (350Z, V35 350GT)Invidia 350Z Decat Test Pipe Kit (VQ35DE. Also suits V35 Skyline) DOES NOT FIT HR ENGINES. View this listing for the HR model. The factory exhaust will always have restrictions and these restrictions are normally highest near where the catalytic converter is found. The Invidia 350Z Decat Test Pipe Kit uses a larger pipe diameter and smooth bends which allows exhaust gases to pass with fewer restrictions and turbulence. A High Flow catalytic converter