BMW M5 / M6 (E60 / E63) | Infinity Design | 100% Equal Length Headers

Infinity Design V4 Equal Length Headers – BMW E90 / E92 / E93 M3 S65 The Infinity Design V4 Equal Length Headers represent the latest evolution of Infinity Design's proven exhaust manifold package for the BMW E9X M3 and its naturally aspirated S65 V8. Building on the worldwide success of the V3, the V4 isn't about chasing a larger headline horsepower figure. The previous V3 has already demonstrated consistent 30–40 hp gains across numerous independently dyno-tested vehicles around the world. Instead, the V4 was developed with a different objective: To refine every aspect of the header design as far as possible. Using detailed 3D scans of the S65 engine and E9X engine bay, the complete system was developed in CAD before being manufactured in-house by Infinity Design. The result is a true 100% equal-length header system with 730 mm primaries, increased internal volume, stepped pipe diameters, larger F1-style collectors, CNC-machined transition flanges and improved access for installation. 100% Equal-Length Primary Design The V3 was already extremely close to being perfectly equal length – close enough to comfortably fall within what is generally considered an equal-length design within the automotive industry. For the V4, Infinity Design took this one step further. Every primary pipe now has an identical 730 mm centre-radius length. This creates a genuinely equal exhaust path from each cylinder head port to the collector, helping maintain consistency in exhaust pulse timing across all eight cylinders. The revised configuration also subtly changes the character of the exhaust, producing a slightly smoother and more harmonised V8 tone. Stepped 42–45 mm Primaries Primary pipe dimensions have also been revised. The previous V3 used 41.7 mm primary pipework. For the V4, this has been increased to 42 mm, before progressively stepping to 45 mm as the primary approaches the collector. This stepped design increases the overall volume of the header while maintaining an appropriate primary size closer to the cylinder head. The result is additional flow capacity further downstream without simply fitting an excessively large primary pipe throughout the entire system. Larger F1-Style Collectors At the end of the eight equal-length primaries sit Infinity Design's redesigned slip-on F1-style collectors. For the V4, the collectors have been substantially increased in both length and internal volume, using larger 45 mm pipework. The combination of true equal-length primaries and increased collector volume creates a carefully controlled route for the individual exhaust pulses as they merge downstream. This revised geometry has been developed not necessarily to increase peak horsepower over the already highly effective V3, but to create a more refined and capable exhaust manifold for a wider range of S65 specifications. Designed for Standard & Large-Displacement S65 Engines One of the major reasons for increasing the overall internal volume was to accommodate the continued development of the S65 platform. The V4 remains perfectly suited to a standard-displacement engine or an S65 equipped with conventional bolt-on performance upgrades. However, its increased capacity becomes particularly valuable on larger-displacement engine builds. The system has been designed with increasingly popular stroker engines in mind, including extreme 5.5-litre through to 5.8-litre S65 builds. As displacement increases, so does the volume of exhaust gas that must efficiently pass through the headers. The V4 provides the additional capacity required to support these applications while remaining effective on a standard engine. CNC-Machined Transition Flanges Airflow development begins directly at the cylinder head. The V4 uses precision CNC-machined flanges incorporating a carefully designed internal taper. The S65's oval exhaust port is progressively transitioned into the 42 mm outside diameter primary pipe, rather than forcing the exhaust gases through an abrupt change in shape. This creates a smoother route from the cylinder head into each primary, reducing unnecessary disturbance at one of the most critical areas of the header. Developed Using 3D Scanning & CAD Packaging eight 730 mm equal-length primary pipes within the confines of an E9X M3 engine bay is a significant engineering challenge. Infinity Design began the V4 development process by 3D scanning the engine and surrounding engine bay. This data was transferred into CAD, allowing the complete primary routing to be developed accurately around the available space. This approach allowed Infinity Design to optimise: Primary pipe length Primary routing Collector positioning Engine and chassis clearance Overall exhaust volume Cylinder-head stud access Installation requirements The result is a header designed around the actual available space rather than a system fabricated through trial and error. Designed & Manufactured In-House The V4 is both designed and manufactured by Infinity Design within its own facility. Keeping the complete process in-house provides direct control over design, fabrication and final quality. Each system uses high-end argon gas-purged welding with full penetration, helping create clean, strong and consistent welds throughout the header assembly. This is particularly important for a component exposed to extreme exhaust temperatures, vibration and repeated thermal cycling. Easier Installation Performance wasn't the only area addressed during the V4 redesign. A major improvement has been made to cylinder-head stud and retaining-nut access. Careful primary routing means that all retaining nuts can now be accessed using normal workshop tools, provided the correct primary installation sequence is followed. This makes the V4 considerably easier to install and service while retaining the complex equal-length primary geometry. Proven 30–40 hp Performance The previous V3 header has consistently demonstrated gains of approximately: +30–40 hp These results have been recorded across numerous vehicles on independent dynamometers around the world. Importantly, Infinity Design isn't claiming that the V4 suddenly produces additional peak power simply because it is a newer product. The V3 already delivered the required performance. The V4 is instead about improving the engineering around that proven concept – true equal primary lengths, increased volume, larger collectors, smoother cylinder-head transitions, improved installation and greater capacity for large-displacement engines. Why the V4? The V4 represents refinement rather than reinvention. Key features include: Developed specifically for the BMW E9X M3 S65 V8 Evolution of the globally proven V3 design V3 demonstrated consistent 30–40 hp gains 100% equal-length primary pipes 730 mm centre-radius length on every primary 42 mm primary pipe diameter Stepped to 45 mm approaching the collector Increased overall internal volume Larger F1-style slip-on collectors Increased collector length and volume CNC-machined cylinder-head flanges Smooth transition from oval exhaust port to round primary Developed using detailed 3D scanning CAD-designed primary routing High-end argon gas-purged welding Full-penetration welds Designed and manufactured in-house Improved cylinder-head stud access Installation using conventional workshop tools Slightly smoother and more harmonised exhaust tone Suitable for standard and modified S65 engines Designed to support large-displacement builds up to 5.8 litres Manufacturing Lead Time Each V4 header system is manufactured at Infinity Design's own facility. Current manufacturing lead time is approximately six weeks as of April 2026. Lead times can vary depending on production demand, so please contact PERON before ordering if the headers are required for a specific build or workshop date. Infinity Design x PERON At PERON, we work closely with Infinity Design, supporting development through technical feedback, vehicle testing, datalogging and access to the PERON Technology Centre and our in-house Dynojet 424x linked dyno facility. The V4 demonstrates the engineering-led philosophy behind Infinity Design. Rather than replacing a successful V3 simply to advertise a larger horsepower figure, Infinity Design has concentrated on perfecting the details – from 730 mm true equal-length primaries and stepped pipework through to collector volume, port transitions, fabrication quality and installation access. For standard, modified and large-displacement S65 builds, the V4 represents the most developed version of Infinity Design's equal-length header package to date.