Precat and exhaust manifold off of my 2003 Nissan maxima (restrictive & has a different design from the obx after market y pipe and different design from 4th gen maxima y pipe. If you take your precat off a 5.5 gen maxima you’re going have to replace both manifold and precat with 4th gen manifold and use a flange pipe like mine to delete the precat or get a warp speed y pipe I heard it’s all put together)