HKS Equal Length Catted Header System - 2013+ FR-S / BRZ / 86

Equal Length Catted Header System for the 2013+ FR-S, BRZ, and 86

The HKS Equal Length Catted Header System for the 2013+ Scion FR-S, Subaru BRZ, and Toyota 86 addresses one of the most significant exhaust flow limitations on the FA20 platform. The factory unequal length headers. The OEM headers on the boxer four are a compromise between packaging and performance, with unequal primary tube lengths that create pulse interference in the exhaust system. Equal length headers eliminate this interference, allowing each cylinder's exhaust pulse to exit without colliding with adjacent pulses, which improves mid-range torque and top-end power.

Specs & Highlights

• Equal length primary tube design
• Eliminates exhaust pulse interference from unequal length OEM headers
• Integrated catalytic converter
• Significant mid-range and top-end improvement on FA20
• Stainless steel construction
• Fitment: 2013+ Scion FR-S / Subaru BRZ / Toyota 86

45mm Equal-Length Primaries, 400 cpsi Metallic Cat

The HKS equal length headers use 45mm primary tubes, up from the factory's unequal primaries that range from approximately 38mm to 42mm, with a single-piece 4-into-1 merge collector. Primary tube length is equalized at approximately 600mm per cylinder. The integrated catalytic converter meets CARB OBD II requirements. System weight is approximately 8.2 kg versus the factory header and front pipe assembly weight of approximately 10.5 kg. Documented dyno gains on an otherwise stock FA20 are consistently 10–18 whp with the biggest gains in the 4,500–6,500 rpm range.

Why Equal Length Headers Work on the FA20

The equal length header is widely regarded as one of the highest-return modifications on the FA20 platform because the factory header is such a significant restriction and interference source. The improvement is not just in peak power. The torque curve broadens and mid-range response improves noticeably because the engine is breathing more efficiently across the RPM range.

10-18 whp Gain, Best Return on the Platform

The catted version retains emissions compliance while still delivering the full performance benefit of the equal length design. Installation is a header replacement at the front of the exhaust system and requires more labor than a simple cat-back swap, but the results justify the additional work. A tune after installation extracts maximum benefit from the improved flow.

The FT Breakdown

The equal length header is often cited as the single most effective bolt-on modification for the naturally aspirated FA20. HKS's version combines the equal length design with a quality catalytic converter, solid construction, and proper fitment for the FA20 application. If you are building a performance FA20, the headers are the starting point. The 10–18 whp gain on a stock-compression naturally aspirated FA20 from equal length headers alone is the strongest argument for doing headers before an exhaust system. The factory headers are such a significant source of pulse interference that addressing them first gives you more power than any cat-back swap alone. The two should ultimately be paired — the header-back build is the correct scope — but if budget requires sequencing, headers come first.