SPELAB Exhaust Header for 2002-2006 Subaru Impreza WRX/STi Sedan/Wagon 4-Door 2.0L 2.5L Replacing or upgrading your exhaust header is necessary for both engine performance and sound. Whether on or off the track, exhaust headers provide more horsepower and improved exhaust sound. SPELAB offers many products to help you create your own custom engine headers. It's really easy and convenient to use: direct bolt-on, no modification needed. Fitment: 2002-2006 Subaru Impreza WRX/STi Sedan/Wagon 4-Door 2.0L 2.5L Specifications: Brand Name: SPELABCertificate: ISO9001:2000Application: Automobile Exhaust HeaderMaterial: Stainless SteelSurface: Mirror PolishModel: EH28015Inlet / Outlet size: 1.5" / 2" Exhaust Header vs. Manifold: Which One is the Superior Choice for Performance? Exhaust headers and exhaust manifolds differ primarily in their material, design, and impact on engine performance. Material and Design:Exhaust headers are crafted from lightweight, thinner steel, making them lighter and more efficient in heat dissipation. In contrast, exhaust manifolds are made from thicker, more durable iron, which is heavier and retains more heat. This material difference plays a significant role in engine performance and efficiency. Size and Configuration:Exhaust headers are typically longer than exhaust manifolds and consist of individual tubes for each engine cylinder. This design allows each exhaust gas pulse to exit the engine independently, reducing the creation of backpressure. On the other hand, exhaust manifolds have a shorter, more compact design, with all the cylinders sharing a single exhaust passage, which leads to higher backpressure and decreased performance. Performance Benefits:Exhaust manifolds, due to their shared exhaust path, create backpressure that can restrict the engine’s ability to expel gases efficiently, leading to reduced horsepower and throttle response. Exhaust headers eliminate this issue by providing each cylinder with its own exhaust pipe, allowing for a more direct and efficient flow of gases. This leads to an increase in engine performance, offering more power and improved overall efficiency. Why Exhaust Headers Are the Better Choice:For those looking to maximize engine power and performance, exhaust headers are the superior option. They reduce backpressure, improve exhaust flow, and increase horsepower and torque. The ability of exhaust headers to facilitate smooth gas flow without interference from other cylinders makes them the ideal choice for high-performance vehicles and enthusiasts seeking to get the most out of their engine. In conclusion, exhaust headers outperform exhaust manifolds in terms of performance and efficiency. While exhaust manifolds may be a more cost-effective and practical solution for stock vehicles, exhaust headers are the better choice for maximizing engine potential, especially in modified or high-performance applications.