For Nissan Altima V6 Stainless Steel Dual 4" Rolled Tip Catback Exhaust System TIG Welded CNC Machine Flange for Resistance Against Pressure and Corrosion Aggressive Deep and Smooth Tone Sound while Ensures Smooth Exhaust Gas Flow Dyno Proven to Instantly Increase 15 to 25 Horsepower or Low End Torque 4"(OD) Muffler Rolled Tip / 2.5"(ID) Inlet / Double Walled Muffler Tip Fit 07-12 Nissan Altima 3.5L V6 Sedan Models ONLY (Instruction NOT Included, Professional Installer is Highly Recommended)