Valvetronic Designs 400-Cell Catted Downpipes for the BMW F80 M3, F82 M4, and M2 Competition are designed to deliver increased performance without sacrificing refinement. Featuring high-flow 400-cell metallic catalysts, these downpipes reduce exhaust restriction while maintaining catalytic functionality.The result is improved turbo response, stronger mid-range pull, and a deeper, more aggressive exhaust tone compared to factory components. Unlike catless systems, the 400-cell design helps retain a more controlled exhaust smell and improved daily usability.Manufactured from premium stainless steel for long-term durability, these downpipes are engineered for direct bolt-on installation using factory mounting points. Tuning may be required to prevent check engine lights and to maximize performance gains.