The original manifold was designed to work with a Stand Alone or a Parallel Setup like in our E46 kits. Which is why you are seeing a second generation manifold. After realizing how far out the Infinity was we decided to speed things up with the piggyback that Vishnu makes. Everything since that point has been working towards using the piggyback system which needs independent O2 readings to work properly with the stock DME. More updates to come guys.
Also their are other ways to make this manifold but we didn't want to make it more complicated just to be different. Having both collector banks up top so you could change out the O2 sensors with ease was just a no brainer.
