it isnt necessary, i have mine disabled in the PCM and have all the equipment removed. it actually has a port stuck into the exhaust manifold that restrict flow! imagine putting your finger 2" into the exhaust flow both in the front and rear manifolds.... that is what the air injection is doing! its purpose is to put fresh air into the exhaust to raise exhaust temps so the cat heats up faster... on the 97 Z34 with the DOHC the engine doesnt even have the pluming for the air injection system.