Why do Subarus have unequal length headers?

An equal length Subaru WRX/STi header will expell gases at an equal rate per pulse, with gas from each cylinder leaving the header at the same time. With an unequal length header, gas from the two longer runners will remain in the header as it will take longer to reach the collector.

Does the Subaru have unequal headers stock?

The factory header for most US market turbo EJ20 / EJ25 Subarus including the WRX, STI, FXT (Forester XT), LGT (Legacy GT), Baja Turbo, and Outback XT are unequal length.

Do twin scroll turbos need equal length headers?

Equal length headers are going to be more efficient for feeding a twin scroll turbo. The exhaust pulses will be equally spaced out and will therefore keep the turbo spinning at a linear rate.

What is a twin-scroll turbo?

Conventional single-scroll turbochargers route those irregular pulses of exhaust into the turbine in a way that causes them to collide and interfere with one another, reducing the strength of the flow. In contrast, a twin-scroll turbocharger gathers exhaust from pairs of cylinders in alternating sequence.

What is the Tomei exhaust manifold?

This is the Tomei Expreme Unequal Length Exhaust Manifold. This is a direct replacement for your factory exhaust manifold to save weight, improve the exhaust flow while producing an aggressive sound and provide an increase in both horsepower and torque.

Will Tomei expreme UE length exhaust manifold fit 2009 Impreza Outback Sport?

Will this Tomei Expreme UE Length Exhaust Manifold fit a 2009 Impreza Outback Sport with 2.5 L engine? A: This header will bolt to your heads, but nothing behind the header would match up. It would need to be a custom made exhaust from header back.

What’s in the box with the Tomei expreme?

Designed for optimum operating efficiency Bolts, Gaskets and Heat Wrap are all included Extreme heat resistant. What’s in the box? The TOMEI Expreme exhaust manifold has been developed to deliver “absolute power” improvement through its efficiency. The performance curve proves that this is the absolute best performance possible from any manifold.

What are the benefits of a new exhaust manifold?

This is a direct replacement for your factory exhaust manifold to save weight, improve the exhaust flow while producing an aggressive sound and provide an increase in both horsepower and torque.