For Subaru WRX GD/GG Stainless Steel 4" Rolled Muffler Tip Catback/Turbo Back+Downpipe+Up Pipe Exhaust System Made of High Quality T-304 Stainless Steel with Computerized Mandrel-Bends for Strength and Durability 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 / 3"(ID) Inlet / 3"(ID) Main Piping / 14mm Thick Double Walled Muffler Tip