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