RS-2: The RS-2 Series has a diamond-shape muffler and includes a straight, single-core baffle. Maximized internal volume. USFS-approved 96dB spark arrestor installed. RS-3: The RS-3 Series has a oval-shape muffler including a straight, single-core baffle. Maximized internal volume. USFS-approved 96dB spark arrestor installed. RS-2 Muffler Options: Aluminum sleeve with stainless steel end-cap Titanium sleeve with stainless steel end-cap RS-3 Muffler Options: Stainless sleeve with aluminum end-cap Titanium sleeve with carbon end-cap