Skunk2 Racing [17-20 Civic Si] Pro-ST Coilover Set - 10K/8K Spring Rates

Engineered to racing specifications, tested and proven over decades on winning racing teams. Integrating the highest-level technologies into an affordable street-spec coilover, our systems are a perfect, affordable solution for your daily driven performance vehicle. Built with daily driven sports cars in mind, our Pro-ST shock absorbers are shorter than factory, lowering the vehicle approximately 3- inches while still retaining full shock travel. This, coupled with the 12-way damping adjustability and stiffer springs, allows you to adjust to the perfect setting for the driving environment. Large 52mm seamless carbon steel mono-tube shock bodies provide strength and provide room for a larger hydraulic piston and valves, more shock oil, and an enlarged nitrogen chamber. All of these upgrades add up to huge jumps in compression and rebound response, vastly improved handling characteristics, and extreme durability even in the harshest of conditions. Externally, the shock bodies are threaded along their length to fit spring preload adjustment collars and the internally threaded lower shock mount and collar. This allows for independent changes in ride height and spring preload, giving the ability to tune each corner's weight to achieve optimal 4-wheel corner balance without sacrificing ride quality. Additionally, the shock body and threads are protected from the elements with gold-colored zinc electroplating. After rigorous testing, we chose to fit linear rate springs instead of progressive. Featuring spring rates of 10kg/mm up front and 8kg/mm in the rear, the linear spring offers more consistency under all different measures of weight loading while cornering and hitting bumps. This offers the most predictable vehicle feedback in all driving situations. Each spring is made from the highest quality AE9254V Chrome Vanadium forged to work with our oil-nitrogen filled strut to provide the greatest possible balance of street and track performance. Pro-ST Coilover Shock Absorber Set; Front 10K/Rear 8K Spring Rates; Set of 4;

• Independent Pre-Load/Ride-Height Adjustments
• 12-Way Adjustable Mono Tube Design
• Billet Aluminum Spring Perches
• Excludes Integra Type R
• 10K/10K Spring Rates
• Set Of 4

Engineered to racing specifications and developed for daily-driven performance vehicles, the Skunk2 Racing Pro-ST coilover system delivers adjustable handling, lowered ride height, and dependable street-to-track performance for the 2017-2020 Honda Civic Si. Part number SKK541-05-8780 includes a complete set of four coilover shock absorbers.

• Independent spring preload and ride-height adjustment
• 12-way adjustable monotube shock design with linear-rate springs

The Pro-ST shock absorbers use shorter-than-factory bodies to lower the vehicle approximately 3 inches while retaining full shock travel. Twelve-way damping adjustment allows the setup to be tailored to changing road and driving conditions, while the stiffer linear-rate springs provide consistent feedback during cornering, braking, acceleration, and bump impacts. This application features 10K front and 8K rear spring rates as listed for the complete set.

Large 52 mm seamless carbon steel monotube bodies provide room for a larger hydraulic piston, optimized valving, increased shock oil capacity, and an enlarged nitrogen chamber. These features support improved compression and rebound response, enhanced handling control, and long-term durability. Threaded shock bodies use billet aluminum spring perches and allow independent adjustments to spring preload and ride height, helping optimize corner balance without requiring the two settings to be changed together. Gold-colored zinc electroplating helps protect the shock bodies and threads from the elements.

Each linear-rate spring is manufactured from AE9254V chrome vanadium material and designed to work with the oil- and nitrogen-filled struts for a predictable balance of street comfort and track performance. This Pro-ST coilover set fits 2017-2020 Honda Civic Si models and excludes Integra Type R applications.

Features:

• Application: Fits 2017-2020 Honda Civic Si models
• Construction: 52 mm seamless carbon steel monotube shock bodies
• Adjustability: 12-way damping adjustment with independent preload and ride-height settings
• Spring Rates: 10K front and 8K rear linear-rate springs
• Ride Height: Lowers the vehicle approximately 3 inches while retaining full shock travel
• Components: Billet aluminum spring perches and gold-colored zinc-plated shock bodies
• Quantity: Complete set of four coilover shock absorbers
• Fitment Note: Excludes Integra Type R applications

Air Freight Prohibited: false
Not Carb Approved: false
Ltl Freight Required: false
Prop 65: Y
Part Type: automotive
Epa: N/A
Carb Acknowledgement Required: false
Regular Stock: t
Units Per Sku: 1
Fitment:
Honda Civic Si 2017
Honda Civic Si 2018
Honda Civic Si 2019
Honda Civic Si 2020

At JDMuscle, we understand that fast and reliable shipping is crucial. With multiple distribution centers across the nation, most in-stock items are shipped within 1-2 business days. On average, you can expect delivery within 1-5 business days for in-stock items. Please note, however, that some products may ship directly from vendors, which could result in additional delays. Products sourced from overseas may also take longer to arrive.

Free Shipping over $199 Policy

• Free shipping is available only for the 48 contiguous states in the U.S.
• Ground shipping applies to regular-sized items only.
• Oversized items such as lips, hoods, and trunks requiring freight shipping are not included in the free shipping program.
• Some manufacturers may impose a shipping surcharge, which will be excluded from the free shipping program.
• The most accurate shipping costs will be displayed at checkout. If you believe the shipping cost is incorrect, please contact us at sales@jdmuscleusa.com for further review.

Carriers

We ship via FedEx, UPS, USPS, and DHL. While we strive to use the most efficient option, we cannot guarantee which carrier will deliver your order. Your items may arrive in multiple packages through different carriers.

Processing Time and Shipping Cut-off

Orders typically take 24 hours to process, with shipping cut-off at 3:00 PM EST. Transit times vary based on location and carrier. Some items, especially those requiring freight shipping, may have extended processing and delivery times. For freight shipping inquiries, contact us at sales@jdmuscleusa.com.

 

International and Special Shipping Considerations

• International orders are subject to higher shipping fees. If you would like to review your shipping cost, email us at sales@jdmuscleusa.com with your full address and items you plan to purchase.
• In some cases, shipping costs may be incorrectly calculated for international or oversized items. We reserve the right to adjust the shipping fee and will work with you to negotiate a fair cost if needed.
• Customers can challenge and request a review of international shipping fees, and we’ll do our best to find a lower rate where possible.
• Customs Fees & Import Taxes: The shipping charge you pay does not include customs fees or import taxes. These charges vary by country and are the customer’s responsibility. Please check with your local customs office for more details before placing an order.
• Shipping Cost Adjustments: Shipping rates fluctuate, and while we strive to provide the most competitive rates, there may be instances where the shipping cost you paid is significantly lower than the actual cost. In such cases, we reserve the right to request the difference to ensure we cover our basic expenses. We appreciate your understanding and will always aim to keep shipping costs as affordable as possible.

 

Address Modifications and Fees

• Any modifications to a shipping address after an order is placed may be subject to additional fees.
• For single, small packages, the flat fee is $20. For larger or multiple packages, the fee may be up to $60 or more.

Freight Shipping Guidelines

• Freight shipments require you to be present at the time of delivery.
• The delivery driver may provide a delivery receipt (Bill of Lading). It is crucial to inspect the shipment before signing.
• Carefully check the packaging for any visible damage (dents, punctures, rips) and notate it on the Bill of Lading.
• Open the package and inspect the product itself. If damage is found, document it in detail on the Bill of Lading, take photos, and contact the shipping company to initiate a damage claim.
• Do not refuse the shipment. Contact us at sales@jdmuscleusa.com for guidance.
• If the delivery driver is unable to wait for inspection, note this on the Bill of Lading.

Failure to document damages before signing the Bill of Lading will void any claims for refunds or replacements.

Pre-Installation Inspection Policy

We strongly recommend inspecting all parts or items upon arrival before installation. If you identify any damage, imperfections or missing components, report them immediately to sales@jdmuscleusa.com. Do not install the item. Please note that reports of damage, defects, imperfections or missing components after installation will NOT be honored.

Package Protection

We do our best to ensure your items arrive to you safely but sometimes things happen. If you utilized our Checkout+ feature, rest assured that your package is protected! With package protection, in the event that your package is lost, stolen, or damaged while in transit, we will replace it free of charge. To start a shipping claim, please click here.

Need Assistance?

If you have any concerns about shipping costs or transit times, or if you notice discrepancies during checkout, feel free to reach out to us at sales@jdmuscleusa.com. We’re happy to assist you and ensure a smooth delivery experience.

Limited Manufacturer Warranty*

Our policy lasts 30 days. If 30 days have passed since your purchase, unfortunately, we can’t offer you a refund or exchange. To initiate a return, please email us at sales@jdmuscleusa.com.

Eligibility for Returns

✅ Items must be unused and in the same condition as when received.
✅ Items must be in their original packaging.

Non-Returnable Items

❌ Gift cards
❌ Special-order or custom products

How to Initiate a Return

📧 Include the following details in your return request email:

Order Number

Item(s) to be returned

Reason for return

Important Notes:

Do NOT send your purchase back to the manufacturer.

Do NOT return any items without first setting up a return request with us.

Partial Refunds

Partial refunds may be granted under the following conditions:

⚠️ Items not in original condition, damaged, or missing parts not due to our error.
⚠️ Items returned more than 30 days after delivery.

Restocking Fees

Some manufacturers may charge a restocking fee, which includes but not limited to:

ManufacturerRestocking Fee

ESR30%

JDMuscle15%

PLM & Option Lab 20%

 

Cancellations

Before placing an order, please confirm availability.

Cancellations within 7 days may be subject to fees to cover third-party transaction costs.

Once the order has been processed (packaged or tracking generated), cancellations are not allowed. Eligible items may be returned instead.

Special-order items cannot be canceled.

Refund Process

🔄 Once your return is received and inspected, we will notify you of the refund status.
💳 Approved refunds will be credited back to your original payment method within 3-10 business days (depending on the payment provider).

Late or Missing Refunds

🔍 Check your bank statement — sometimes the refund may not appear as a new entry but as the disappearance of the pending charge. 📞 Contact your credit card or financing company — they may require additional time for processing.

If you’ve done all of the above and still haven’t received your refund, email us at sales@jdmuscleusa.com for assistance.

Sale Items

Only full-priced items are eligible for returns and refunds.

Exchanges

We replace items only if they are defective or damaged. To request an exchange for the same item, email us at sales@jdmuscleusa.com.

Gifts

🎁 If the item was marked as a gift when purchased and shipped directly to you, you will receive a gift credit for the return value.
📩 If the gift giver had the item shipped to themselves, we will refund the gift giver.

Return Shipping

📦 Customers are responsible for return shipping costs unless the item is damaged, defective, or incorrect (in which case we will cover shipping both ways).

Initial shipping costs are non-refundable.

Return shipping costs will be deducted from the refund amount.

For items over $75, consider using a trackable shipping service or purchasing shipping insurance. We are not responsible for lost or damaged items during return shipping.

Return Shipping Address: Please use the address provided in the RMA/return instructions, as it may differ from the initial shipping address.

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