SP Concepts' Big Bore 4.5 2-into-1 for M8 baggers — stepped headers and a reversion chamber feeding a 4.5-inch high-flow muffler, built for everything from stock motors to big-inch builds. Pro Flo chambers are available on this system as an option.
FITMENT
Fits every 2017–2026 Harley-Davidson Touring model, including all CVO models and the 2024 models with VVT and updated engine covers (fitment as published by SP Concepts).
Not sure it fits your bike? Email info@norcalbaggersupply.com — email is the fastest way to reach us — and we'll confirm before you order. You can also call 916-626-9030 (Mon–Fri, 9 AM–5 PM PT).
CALIFORNIA NOTICE
Race use only — not legal for use in California. SP Concepts labels this system a “Competition Use Only / Race Ready” product. It does not conform to California Air Resources Board (CARB) standards, carries no CARB Executive Order, and does not contain a catalytic converter. It is not legal for use on pollution-controlled vehicles operated on public streets or highways in California, and we cannot ship it to a California address — orders shipping to California will be cancelled and refunded. Available for shipment to the other 49 states.
SPECIFICATIONS
Manufacturer: SP Concepts (Stainless Powered Concepts) — Lake Elsinore, California, USA
SP Concepts part number family: SPC-2-003 (each finish carries its own part number, shown on its variant)
System type: 2-into-1 full exhaust system
.065 stainless steel headers, stepped from 1¾″ to 1⅞″ to 2″ at the collector
Hand TIG welded; machined stainless steel header collars
18mm O2 bungs with 12mm adapters — allows stock or autotune sensors
Complete hardware kit included — everything needed to mount it up
4.5″ high-flow performance rolled cone muffler with a stepped baffle from 2¼″ to 2½″ — increases bottom to mid range torque and horsepower
Finish options: Stainless, Black, Polished, Black ONYX, Platinum
Reversion chamber after the collector (per SP Concepts)
Optional Pro Flo chambers (see the Add Pro Flo Headers option)
INSTALLATION
Install using the included complete hardware kit. SP Concepts' official install video for their 2-into-1 exhaust systems — the video SP links from its own FAQ install guide — is embedded below.
QUESTIONS RIDERS ASK
What do the Pro Flo chambers do? Per SP Concepts, the Pro Flo chambers are designed to aid in the reversion and expansion process and help produce better torque and horsepower numbers than the standard system.
Which motors can this system handle? Per SP Concepts, it increases bottom to mid range torque and horsepower on all motors, and tuned properly it can accommodate 88″ to 143″ engines.
Can you ship this to California? No. This is a race-use-only part that does not conform to CARB standards, so we do not ship it to California — see the California Notice above. It is available to the other 49 states.
