For Subaru Impreza WRX Stainless Steel Turbo Downpipe - 5-Bolt Application: 02-07 Subaru Impreza WRX Inlet: 4.375" x 2.25" (Oval)/ Outlet: 3" / Piping Diameter: 3" TIG welded CNC machine flange for strength and durability Made of high quality T-304 stainless steel with computerized mandrel-bends Increase engine output and efficiency. Gain 10 - 15 HPs (approximately)