An apparatus and system are disclosed for ensuring proper assembly of an exhaust system. Ensuring proper assembly of an exhaust system is accomplished by providing an inflow exhaust subassembly for receiving engine exhaust, at least one intermediate subassembly that selectively mates and rotationally aligns with the inflow subassembly and receives engine exhaust therefrom, the at least one intermediate subassembly further configured to selectively mate according to a pre-selected alignment with an outflow subassembly, and the outflow subassembly configured to receive engine exhaust from the at least one intermediate subassembly. In certain embodiments, the at least one intermediate subassembly comprises a plurality of intermediate exhaust subassemblies each configured to selectively mate with adjacent subassemblies according to a pre-selected order and alignment.