Two Brothers Racing’s unique muffler packing is a crucial performance part. When fresh, it allows your top-level exhaust system to deliver power efficiently while producing the best custom sound from your machine. New packing also ensures your custom exhaust system lasts for years. Every TBR muffler is hand-packed with our high-quality damping material at our factory, and you can have the same, new-system results every time you service your muffler. Our complete Repack Kits include everything you need to restore your Street, MX, or ATV muffler to factory-fresh performance levels. We recommend replacing the packing after every 10 hours of use.