From pro touring to pro mod, if you have a next-level, no-corners-cut build and are looking for a custom finished harness to match, look no further. We offer the full run of options to save you time, eliminate guess work, and to help you unlock the full potential of your Holley EFI system.
What sets our custom harness apart from an off-the-shelf unit:
True Custom Build
- Every lead is planned and built to the exact specs of your combo for a perfect fit - Style of intake and throttle, sensor placement, style of crank pickup, etc.
- Builds available for most popular domestic V8 engines and more.
Full Advantage Capabilities
- Pre-wired and fully terminated inputs and outputs, to your exact requests, for a true plug-and-play wiring job - boost control, nitrous, trans brake, staged injectors, flex fuel, shock travel, air conditioning... The list goes on
- Fully-sealed and super compact relay block attached standard, with a dedicated fuel pump relay separate from the EFI relay, and three open-use relays at bare minimum.
- Next-level options available including firewall bulkhead disconnects, plug-and-play switch panel integration and more
- CAN bus connection terminated with power and ground integrated
The Best Materials
- US-made TXL wire used throughout
- Military grade tefzel cable used on all shielded leads
- High-quality braided loom with heat shrink on lead ends and breakouts - No ugly electrical tape.
- Permanent white-on-black labels on all major engine and sensor connections for guess-free installation season after season
- High temp heat boot on wideband O2 end(s) standard
*Due to the countless options available, this $50 purchase is a fee to quote you a custom system. Once we receive your purchase, we'll send you our interactive form for you to build your system and choose specs exactly as you want. Once we receive your answers, we'll send you a fully itemized and detailed estimate, custom-tailored to give you the best possible combo based on your requests. We'll then go over final details, and give you the option to move forward with the build.
Please note that the $50 fee is NON-REFUNDABLE and NON-TRANSFERABLE. However, it will be put towards the purchase of your system should you decide to move forward, and is good for 90 days once estimate is received.
Pricing starts at $624.95 plus shipping. This includes the base-level main harness with attached relay block and a modular injector harness to match your injector style. Systems are custom-built per order, and final pricing will vary depending on custom options and features, and input / output load out.