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Ignitions and Electrical› Wiring Harnesses
Holley
HARNESS KIT, UNIVERSAL V8 MPFI
SKU: H00E 558-504
Moderate — 2–4 hours
Overview
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Part #: 558-504
An EFI system depends heavily on being supplied a clean and constant voltage source. The grounds of an electrical system are just as important as the power side. Our Holley EFI Harness Kit comes complete with the main harness, power harness and injector harness to support your primary system!
Features:
- Harness Kit Includes; Main Power Harness, Universal MPFI Main Harness, v-8 Injector Harness
- Simple installation
- Works with HP or Dominator ECU's
Universal V8 MPFI
Product descriptions are provided by our supplier partners and may not always be perfectly accurate. Not sure this fits? or call (760) 282-4645 and we’ll verify before you order.
Fitment
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Specifications
| Brand | Holley |
| Part Number | H00E 558-504 |
| Weight | 5.55 lb |
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Returns & Fitment
Built for enthusiasts. Every order is backed by our 30 day return window on eligible items. Unused and uninstalled products may be returned with approved RMA and no restocking fees when received in new condition. Orders placed through the MOTORMIA app with a complete build qualify for our Fitment Guarantee — free return shipping if the part doesn’t fit your exact setup. The guarantee covers fit only; installation must follow manufacturer instructions, and we recommend a qualified shop for parts marked Difficulty 4–5.
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