Skip to Product Info
    • 558-306_05 (1).jpg
    Sale!

    Holley Universal Unterminated Ignition Harness, for HP EFI & Dominator EFI | 558-306

    Vendor: Holley EFI
    Part Number: 558-306
    Save $25
    Sale Price $194.95 Regular Price $219.95

    Available to order. In-stock orders typically ship in 1 to 2 business days.

    Not sure it fits your vehicle?
    Email sales@berryperformancesales.com with your year, make, model and engine, and we'll help you check fitment before you order.
    Fast Fulfillment: In-stock orders typically ship within 1 to 2 business days.
    Free Shipping on Orders Over $99 | Excludes freight shipments
    International Shipping Available: email sales@berryperformancesales.com for a quote.
    Payment & Security

    Secure, encrypted checkout. Card details go straight to the payment processor and are never stored by us.

    • Amazon
    • American Express
    • Apple Pay
    • Diners Club
    • Discover
    • Google Pay
    • Mastercard
    • PayPal
    • Shop Pay
    • Venmo
    • Visa
    Share to:

    This unterminated ignition harness gives builders a universal starting point for wiring custom ignition setups into a Holley HP EFI or Dominator EFI system, leaving termination up to the installer for maximum flexibility.

    Specifications:

    • Application: Universal
    • Compatible ECUs: HP EFI, Dominator EFI
    • Termination: Unterminated (installer-terminated)
    • Harness Type: Ignition
    • Part Number: 558-306

    FAQ

    What does "unterminated" mean for this harness?

    It ships without connectors installed, so the installer terminates it to match their specific ignition components.

    Which ECUs is this compatible with?

    Holley HP EFI and Dominator EFI.

    Why choose an unterminated harness over a pre-terminated one?

    It offers flexibility for custom or non-standard ignition setups that don't match Holley's pre-terminated application-specific harnesses.

    Shipping Policy
    • Free shipping on orders over $99 (excludes freight shipments).
    • In-stock orders typically ship within 1 to 2 business days. Weekend and holiday orders are processed the next business day.
    • Orders ship from Defiance, Ohio and a nationwide network of warehouses and manufacturers.
    • Items showing an ETA are not in stock yet. ETAs come from the manufacturer and can change.
    • No P.O. Boxes. International orders need a shipping quote, so email us first.

    Read the full Shipping Policy

    Return Policy
    • 30-day return window from the ship date. Returns must be approved first; email sales@berryperformancesales.com with your order number.
    • Items must be unused, complete and in the original packaging.
    • A 20% restocking fee applies, and return shipping is paid by the buyer.
    • Not returnable: installed or modified parts, opened or used programmers and tuners, custom orders, Open Box, and Clearance or Final Sale items.
    • Damaged, defective or incorrect items must be reported within 48 hours of delivery with photos.

    Read the full Return Policy

    Disclaimer

    All products are sold for off-road use only unless otherwise specified. Buyer assumes all responsibility for installation and operation. Seller is not liable for any incidental, indirect, or consequential damages — including engine failure, labor costs, or vehicle downtime — resulting from the use of any product sold.

    By making a purchase from Berry Performance Sales, you acknowledge and agree to abide by the terms and conditions of these Policies.

    For any questions or concerns, please contact us — we’re always happy to help.

    Recently Viewed