Bull Boost Performance
GT4 Style Carbon Fiber Rear Bumper Diffuser Lip for Porsche Boxster Cayman 981 13-15
GT4 Style Carbon Fiber Rear Bumper Diffuser Lip for Porsche Boxster Cayman 981 13-15
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Enhance the rear-end styling and aerodynamic character of your Porsche 981 with the STRATEC™ Carbon Fiber GT4 Style Rear Diffuser, engineered specifically for the 2013–2015 Porsche Cayman and Boxster. Drawing inspiration from GT4 motorsport design, this rear diffuser delivers a more aggressive, track-inspired appearance while maintaining a clean OEM-plus fit and finish.
Constructed from high-quality carbon fiber, the STRATEC™ rear diffuser is lightweight, durable, and precision-molded for accurate alignment with the factory rear bumper. The GT4-style fins are designed to help manage airflow underneath the vehicle, contributing to improved rear stability and a more purposeful stance without compromising everyday drivability.
Designed as a direct bumper diffuser lip upgrade, this component follows the factory bumper contours for seamless integration. A UV-resistant clear coat protects the carbon fiber surface, ensuring long-lasting gloss, durability, and resistance to environmental wear.
Key Features
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STRATEC™ carbon fiber construction
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GT4-style motorsport-inspired rear diffuser
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Lightweight aerodynamic bumper lip upgrade
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Improves airflow and rear-end stability
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OEM-style fitment with clean integration
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UV-resistant clear coat for long-lasting finish
Vehicle Fitment
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Porsche Cayman 981 (2013–2015)
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Porsche Boxster 981 (2013–2015)
The STRATEC™ Carbon Fiber GT4 Style Rear Diffuser is the ideal upgrade for Porsche 981 owners seeking a balanced combination of motorsport-inspired design, premium materials, and factory-aligned fitment.
Shipping & Returns
Shipping & Returns
Shipping on most orders in 24-48 hours special orders can be 2-3 days. Returns see Returns Policy.
We have a 30-day return policy on most products, which means you have 30 days after receiving your item to request a return. Some products carry a longer manufacture warranty please contact us if you have questions about items.
To be eligible for a return, your item must be in the same condition that you received it, unused, with tags, and in its original packaging. You’ll also need the receipt or proof of purchase.
To start a return, you can contact us at overthehilltractor@gmail.com. Please note that returns will need to be sent to the following address: 2005 Stuarts Draft Hwy, Stuarts Draft, VA 24477
If your return is accepted at damage or defective, we’ll send you a return shipping label, as well as instructions on how and where to send your package. Items sent back to us without first requesting a return will not be accepted.
If your return is due to no longer needed, wrong size order, ordered by mistake, found better pricing, etc the customer is responsible for the return shipping cost.
Any item returned over $50 cost we suggest insurance on package.
You can always contact us for any return question at overthehilltractor@gmail.com.
Damages and issues
Please inspect your order upon reception and contact us immediately if the item is defective, damaged or if you receive the wrong item, we can only give 72 hours from time package is scanned delivered to accept claims. Please contact within 72 hours of delivery so that we can evaluate the issue and make it right.
Exceptions / non-returnable items
Certain types of items cannot be returned, like fuel related items due to hazardous materials shipping regulations. We also do not accept returns for hazardous materials, flammable liquids, or gases. Please get in touch if you have questions or concerns about your specific item.
Electrical parts can only be returned if new and in original condition, Used electrical parts are not returnable unless actually defective, contact us with details.
Unfortunately, we cannot accept returns on sale items or gift cards.
Refunds
We will notify you once we’ve received and inspected your return, and let you know if the refund was approved or not. If approved, you’ll be automatically refunded on your original payment method within 10 business days. Please remember it can take some time for your bank or credit card company to process and post the refund too.
If more than 15 business days have passed since we’ve approved your return, please contact us at overthehilltractor@gmail.com.
Most items are covered by 30 day warranty, Fuel Related parts are only covered against actually manufacture defect since the fuel produced today breaks down gaskets and seals quickly. Electrical parts can only be returned if new and in original condition, Used electrical parts are not returnable unless actually defective, contact us with details. Returns are handled on each individual item, some items will not require return for refund just that customer submit picture of proof of issue. Please contact us with questions about returns.

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Free Shipping
Free shipping on orders over $150
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