Question 1

How do I place an order?

Accepted Answer

Browse our shop by category or use the search bar to find the part you need. Once you have found the right product, confirm the fitment by selecting your engine platform and model year, then add it to your cart. When you are ready, proceed to checkout and enter your shipping and contact details. You will receive an order confirmation email right away, followed by a separate email with payment instructions. Once we confirm your payment, we place your order and ship it — you will get a final email with tracking information once it is on the way.

Question 2

What payment methods do you accept?

Accepted Answer

We currently accept Venmo, Zelle, Cash App, and PayPal (Friends & Family) only — no cards yet. Submit your order at checkout and we will follow up by email with payment instructions, usually within a few hours. All sales are final once payment is confirmed.

Question 3

Do you ship internationally?

Accepted Answer

Our primary focus is domestic US shipping, which allows us to keep costs down and delivery times predictable for the majority of our customers. That said, we do fulfill select international orders to Canada, Australia, and the United Kingdom on a case-by-case basis. International orders are subject to additional shipping costs, import duties, and longer transit times. If you are located outside the US and want to order, contact us at Overkilldieselperformance@gmail.com with your address and the items you need and we will provide a custom shipping quote.

Question 4

How long does shipping take?

Accepted Answer

Most in-stock items ship within one to two business days of us confirming your payment. Standard ground shipping typically takes three to seven business days after that, depending on your distance from our warehouse. Need it faster? Mention it when you submit your order, or reply to your payment instructions email, and we will quote expedited shipping. Large or heavy items such as complete exhaust systems ship on a freight pallet at a flat rate, which can add a few days to the standard transit time. Your exact shipping cost and estimated delivery window are confirmed in the payment instructions email we send after you submit your order.

Question 5

Do you offer free shipping?

Accepted Answer

Yes — standard ground shipping is free on orders over $150 shipped within the continental United States, applied automatically with no coupon code required. Orders shipping to Alaska, Hawaii, or US territories do not qualify for the free shipping threshold and will be quoted separately. Freight items such as complete exhaust systems ship at their own flat rate, which the free-shipping threshold does not waive. If you would like expedited shipping instead, just let us know when you submit your order and we will quote the upgrade.

Question 6

How do I track my order?

Accepted Answer

As soon as your order ships, we email you a tracking number and a direct link to the carrier tracking page. Most shipments go out via UPS or FedEx. If you do not see the email, check your spam folder before reaching out — transactional emails occasionally get filtered. If you still need an update, reply to any of our emails or contact us directly and we will look it up for you.

Question 7

What is your return policy?

Accepted Answer

All sales are final. We do not offer returns, refunds, or exchanges on any order, and payments sent via Venmo, Zelle, Cash App, or PayPal Friends & Family are not eligible for chargebacks or payment disputes. Review your order carefully — engine platform, model year, and any configuration details — before sending payment. If a product turns out to be defective, see our Warranty Policy: manufacturer defects are handled as a warranty claim, not a return.

Question 8

What if I receive a damaged or defective item?

Accepted Answer

Contact us at Overkilldieselperformance@gmail.com as soon as you notice the problem, with your order reference, a description of the issue, and photos if you have them. Shipping damage should be reported right away so we can file a freight claim. Manufacturer defects are handled under our Warranty Policy — we work directly with you and the manufacturer to resolve it.

Question 9

Can I cancel or change my order?

Accepted Answer

Yes — right up until you send payment. Submitting an order does not charge you automatically; we follow up by email with payment instructions, and nothing is final until we confirm your payment. If you need to cancel or change anything before then, just reply to your order confirmation email or contact us directly. Once payment is confirmed and the order is placed, it can no longer be changed or cancelled.

Question 10

How does the tuning process work?

Accepted Answer

Our tuning process starts when you submit your truck details through the tuning order form — engine platform, year, current modifications, power goal, and primary use (daily driver, tow rig, or performance). Our calibrators use that information to build a custom tune file tailored to your specific combination of parts and goals. Depending on the tuning platform your truck supports, the tune is either delivered as a downloadable file you flash yourself using a device you already have, or we ship you a pre-loaded device to plug in and flash. For EFILive, HP Tuners, and similar platforms you will need the appropriate vehicle communication interface. We walk every customer through the install process and are available for support if anything comes up.

Question 11

What tuning platforms do you support?

Accepted Answer

We support the most widely used diesel tuning platforms across all three major engine families. For Cummins applications, we work with EFILive, HP Tuners, and proprietary custom tune formats depending on the year. Duramax trucks are supported via EFILive and HP Tuners across LB7 through L5P. Powerstroke applications are handled through HP Tuners and SCT for most model years. If you have a less common setup — such as a pre-common-rail 12V or 24V Cummins — contact us directly to confirm support before ordering. We are continuously expanding our platform coverage and can often accommodate requests that aren't listed on the website.

Question 12

Can I switch between tune levels?

Accepted Answer

Yes. Our tune packages are designed to include multiple calibration levels on supported platforms. A typical tune delivery includes a daily/economy map for fuel-efficient commuting, a tow map optimized for torque and EGT management under load, and one or more performance maps for maximum power output. You switch between maps using the same device you used to initially flash the tune. The exact number of available maps depends on the platform and the power level you ordered — higher-tier tunes that require supporting hardware modifications are clearly labeled with their prerequisites. If you later upgrade your injectors, turbo, or fuel system, we offer retune services at a discounted rate for existing customers.

Question 13

What engines do you support?

Accepted Answer

We specialize in the three dominant light-truck diesel platforms: Cummins, Duramax, and Powerstroke. On the Cummins side, we cover everything from the 5.9L 12V and 24V through the current 6.7L fifth-generation platform. Duramax support spans LB7 through L5P across Chevrolet and GMC applications. For Powerstroke, we carry parts and tuning for the 7.3L, 6.0L, 6.4L, and both generations of the 6.7L. Many of our products are platform-specific, so always use the year and engine selector on product pages to confirm fitment before ordering. If you have a unique or modified application that falls outside the standard fitment matrix, contact us — we are happy to verify compatibility manually.

Question 14

Do you offer installation services?

Accepted Answer

Overkill Diesel Performance is currently an online-first operation, which means we do not have a walk-in service bay where you can drop off your truck. However, we have relationships with trusted diesel specialty shops in multiple regions around the country who are familiar with our products and tuning. If you need a referral for installation in your area, reach out to us and we will do our best to connect you with a shop we trust. For customers who are comfortable doing their own wrenching, we provide detailed installation documentation with every order and are available by email and phone to answer technical questions during your install.

Question 15

How can I contact you?

Accepted Answer

The fastest way to reach us is through the contact form on our website, which goes directly to our team and is typically answered within a few hours during business hours. You can also email us directly at Overkilldieselperformance@gmail.com for sales questions, technical support, and order inquiries. We monitor our Instagram DMs as well for quick fitment questions and build advice — find us at our handle on the social links in the footer. For urgent order issues such as a damaged shipment or time-sensitive delivery concern, email is the best channel and we will prioritize your request.

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