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  • Flowmaster 20-25 GM 2500HD 6.6L CCB American Thunder Cat-Back Exhaust System - 817933
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Flowmaster 20-25 GM 2500HD 6.6L CCB American Thunder Cat-Back Exhaust System - 817933
Flowmaster 20-25 GM 2500HD 6.6L CCB American Thunder Cat-Back Exhaust System - 817933
Flowmaster 20-25 GM 2500HD 6.6L CCB American Thunder Cat-Back Exhaust System - 817933
Flowmaster 20-25 GM 2500HD 6.6L CCB American Thunder Cat-Back Exhaust System - 817933
Flowmaster 20-25 GM 2500HD 6.6L CCB American Thunder Cat-Back Exhaust System - 817933
Flowmaster 20-25 GM 2500HD 6.6L CCB American Thunder Cat-Back Exhaust System - 817933
Flowmaster 20-25 GM 2500HD 6.6L CCB American Thunder Cat-Back Exhaust System - 817933
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Load image into Gallery viewer, Flowmaster 20-25 GM 2500HD 6.6L CCB American Thunder Cat-Back Exhaust System - 817933
Load image into Gallery viewer, Flowmaster 20-25 GM 2500HD 6.6L CCB American Thunder Cat-Back Exhaust System - 817933
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Flowmaster 20-25 GM 2500HD 6.6L CCB American Thunder Cat-Back Exhaust System - 817933

Exhaust, Mufflers & Tips Catback
Flowmaster
flo817933
Backordered
September 23, 2026
Not CARB compliant. Not legal for sale or use in California on emissions-controlled vehicles.
$1,079.95 $1,257.95
The Flowmaster® American Thunder® Cat-back exhaust system for the 2020-2026 Chevy Silverado and GMC Sierra 2500HD and 3500HD trucks with the 6.6L gas engine, has a moderate to aggressive sound level inside and outside of the truck, with all of the performance benefits you expect from Flowmaster®. Designed for the Crew Cab, Standard Bed (6.5 ft.) models only, this bolt-on, emissions-legal system features a stainless steel 50 Series HD™ muffler and large dual 3.00-inch 409 stainless steel mandrel-bent tailpipes that can be configured to exit either dual straight out the back, or dual out the sides behind the rear wheels which is best suited for towing applications. The system is finished off with a pair of large 4.00-inch polished 304 stainless steel tips and is covered by our Lifetime Limited Warranty. Designed for an easy fit, this system includes all necessary parts and hardware for installation. Fits 2020-2026 Chevy Silverado/GMC Sierra 2500HD/3500HD trucks with 6.6L gas engine. Crew Cab/6.5ft bed only. Will not fit models with 5th wheel tow hitch installed. Features & Benefits Uses the Factory Hanger Locations for Easy Installation Mandrel-bent 16-gauge Tubing for Maximum Exhaust Flow 50 Series HD Muffler with Delta Flow Technology 409 Stainless Steel...
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Flowmaster 14-19 GM1500 5.3L CC&DC SS Outlaw Extreme Cat-Back Exhaust System - 817916
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Flowmaster 20-25 GM 2500HD 6.6L CCB American Thunder Cat-Back Exhaust System - 817933
SKU: flo817933
Product Details

Everything You Need To Know

Review product information, shipping and returns, and price-match details before you order.

Product Info

The Flowmaster® American Thunder® Cat-back exhaust system for the 2020-2026 Chevy Silverado and GMC Sierra 2500HD and 3500HD trucks with the 6.6L gas engine, has a moderate to aggressive sound level inside and outside of the truck, with all of the performance benefits you expect from Flowmaster®. Designed for the Crew Cab, Standard Bed (6.5 ft.) models only, this bolt-on, emissions-legal system features a stainless steel 50 Series HD™ muffler and large dual 3.00-inch 409 stainless steel mandrel-bent tailpipes that can be configured to exit either dual straight out the back, or dual out the sides behind the rear wheels which is best suited for towing applications. The system is finished off with a pair of large 4.00-inch polished 304 stainless steel tips and is covered by our Lifetime Limited Warranty. Designed for an easy fit, this system includes all necessary parts and hardware for installation.

Fits 2020-2026 Chevy Silverado/GMC Sierra 2500HD/3500HD trucks with 6.6L gas engine. Crew Cab/6.5ft bed only. Will not fit models with 5th wheel tow hitch installed.

Features & Benefits

  • Uses the Factory Hanger Locations for Easy Installation
  • Mandrel-bent 16-gauge Tubing for Maximum Exhaust Flow
  • 50 Series HD Muffler with Delta Flow Technology
  • 409 Stainless Steel Construction for Long Life
  • Multiple Tailpipe Exits Provided in Kit
  • Increased Performance and Exhaust Flow
  • Large 3.00-inch Dual Tailpipes
  • Deep Powerful Exterior Sound
  • Lifetime Limited Warranty
  • Flowmaster Quality
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In stock items typically ship within 1-3 business days. Most items arrive within 2 business days, but there are situations where it may take up to 5 business days.

Special Order Items:
Special order and out of stock items are product-specific and lead times can vary. Please e-mail us if you are looking for an ETA / Lead Time on a specific product. Special order orders are subject to cancellation if the vendor cannot provide any ETA.

Returns Policy

To start the return process, please e-mail sales@allianceracing.com

Include the following:
Subject "Return for Order#"
Order Number
Part Number
Reason

Returns are eligible for up to 14 days from delivery of items. Accepted refunds can take up to 7-10 business days to process. All refunds are subject to a 25% restocking fee, if opened. Customer may be responsible for return shipping. If 14 days have gone by since your item was delivered, unfortunately we can’t guarantee you a refund or exchange. We reserve the right to deny any return request, based on provided information.

Alliance Racing is not responsible for ensuring part fitment. It is the responsibility of the purchaser to ensure the parts being ordered are the correct fitment for the vehicle intended. Alliance Racing will not accept any returns for incorrect fitment after product is opened.

To be eligible for a return, your item must be unused and in the same condition that you received it. It must also be in the original packaging.

Shipping

To return your product, mail your product to:
Alliance Racing LLC
8810 Twin Lakes Blvd
Tampa, FL 33614

In many cases, you will be responsible for shipping costs to return your item. Shipping costs are non-refundable. If you receive a refund, the cost of shipping will be deducted from your refund.

Depending on your location, the time it may take for your exchanged product to reach you may vary.

If you are shipping an item over $100, you should consider using a trackable shipping service and/or purchasing Shipping Insurance.

To initiate a price match, please e-mail sales@allianceracing.com with the product information (SKU, URL, & Part Name) and a link to the competitors product page for us to validate the price match eligibility.

Please note that there are cases when we cannot offer a price match, but we will do everything in our power to try to match it. Some manufacturers have Pricing Policies that we have to adhere to.

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