We call it a "system" because we have designed the 3" downpipe assembly with total upgradability in mind. We do this by incorporating the latest technology in materials and componentry. No compromises have been made in building these assemblies. Intergrated V-Band connections for ease of install (SS V-Band clamps included). Includes transition to stock exhaust w/ o2 sensor fitting. Hi-flowing large diameter catalytic converter with SS body.