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18-23 Ford Mustang GT 5.0L V8 Flowmaster 817799 American Thunder Axle-back Exhaust System

Upgrade the 2018-2023 Ford Mustang GT 5.0L with Flowmaster's American Thunder Axle-Back Exhaust System. Designed for factory Active Performance Exhaust, it delivers a moderate tone with valves closed and an aggressive exhaust note when opened. Premium stainless steel construction, quad polished tips, and a direct-fit design provide lasting durability, performance, and unmistakable muscle car styling.

Top Features

  • Part Number: 817799
  • American Thunder axle-back exhaust system
  • Designed for Factory Active Performance Exhaust
  • Outlaw® performance mufflers
  • Moderate sound with valves closed, aggressive sound when opened
  • 3.00-inch mandrel-bent 409 stainless steel tubing
  • Quad 4.00-inch polished 304 stainless steel exhaust tips
  • Reuses factory active exhaust actuators
  • Uses factory hanger locations
  • Includes clamps, hardware, and installation instructions
  • Lifetime Limited Warranty

Vehicle Fitment

  • 2018-2023 Ford Mustang GT Coupe 5.0L V8 with Factory Active Performance Exhaust
  • 2018-2023 Ford Mustang GT Convertible 5.0L V8 with Factory Active Performance Exhaust
Vendor: Flowmaster
SKU: FLO817799
Availability: 7 In Stock
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UPC: 700042037766
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Proposition65 Warning: Cancer and Reproductive Harm

Description

Flowmaster American Thunder Axle-Back Exhaust System for 2018-2023 Ford Mustang GT 5.0L with Active Exhaust

Part Number: 817799

Transform the sound and appearance of the 2018-2023 Ford Mustang GT 5.0L with the Flowmaster American Thunder Axle-Back Exhaust System. Engineered specifically for Mustang GT coupes and convertibles equipped with the factory Active Performance Exhaust, this premium axle-back system delivers the best of both worlds. With the exhaust valves closed, the race-proven Outlaw® mufflers produce a refined yet moderately aggressive tone for comfortable cruising. Open the factory valves and the system unleashes an aggressive, wide-open exhaust note worthy of the Mustang's legendary V8 performance. Constructed from durable stainless steel with large mandrel-bent tubing and finished with quad polished 304 stainless steel tips, this system enhances exhaust flow, improves durability, and gives the rear of the vehicle an unmistakable performance appearance. Designed to reuse the factory exhaust actuators and mounting locations, this high-quality Flowmaster system offers an exceptional combination of performance, sound, fitment, and long-lasting value.

Key Features

  • Designed for 2018-2023 Ford Mustang GT 5.0L models equipped with Factory Active Performance Exhaust.
  • Premium American Thunder axle-back exhaust system.
  • Race-proven Outlaw® mufflers provide moderate sound with valves closed and aggressive sound when opened.
  • Large 3.00-inch mandrel-bent 409 stainless steel tubing promotes improved exhaust flow.
  • OEM-style exhaust valves included for compatibility with factory active exhaust actuators.
  • Quad 4.00-inch polished double-wall 304 stainless steel exhaust tips with embossed Flowmaster logo.
  • Straight-through performance muffler design.
  • Uses factory hanger locations for a precise fit.
  • Includes clamps, hardware, and installation instructions.
  • Manufactured from corrosion-resistant stainless steel for long service life.

Benefits

  • Produces an aggressive muscle car exhaust tone while retaining factory active exhaust functionality.
  • Improves exhaust flow for enhanced overall performance characteristics.
  • Maintains comfortable cruising with valves closed while delivering an exhilarating exhaust note on demand.
  • Adds an aggressive rear appearance with polished quad stainless steel tips.
  • Direct-fit design minimizes installation time and eliminates unnecessary modifications.
  • Built from premium stainless steel materials for exceptional durability and corrosion resistance.
  • Backed by Flowmaster's Lifetime Limited Warranty for long-term peace of mind.

Product Specifications

  • Brand: Flowmaster
  • Part Number: 817799
  • Product Type: Axle-Back Exhaust System
  • Exhaust Series: American Thunder
  • Sound Level: Aggressive / Moderate
  • Vehicle Compatibility: Factory Active Performance Exhaust equipped vehicles only
  • Main Pipe Diameter: 3.00 inches
  • Pipe Material: 409 Stainless Steel
  • Pipe Finish: Natural
  • Muffler Material: 409 Stainless Steel
  • Muffler Finish: Black High-Temperature Paint
  • Muffler Shape: Oval
  • Muffler Quantity: 2
  • Valve Type: OEM-Style Valves
  • Valve Actuators: Reuses factory OEM actuators
  • Exhaust Tip Material: 304 Stainless Steel
  • Exhaust Tip Finish: Polished
  • Exhaust Tip Color: Silver
  • Exhaust Tip Diameter: 4.00 inches
  • Exhaust Tip Length: 5.25 inches
  • Exhaust Tip Style: Double-Wall Round Angle Cut
  • Exhaust Tip Quantity: 4
  • Exit Style: Dual Rear Exit
  • Inlet Connection: Slip-Fit Clamp-On
  • Clamps Included: Yes
  • Hangers Included: Yes
  • Catalytic Converters Included: No
  • California Proposition 65: Yes

Install Difficulty Level

Easy. This direct-fit axle-back system is designed to utilize the factory hanger locations and reuse the OEM active exhaust actuators. All required clamps, hardware, and detailed instructions are included. Basic hand tools and cutting of the factory exhaust are required. Installation can be completed in approximately 1 hour by an experienced DIY enthusiast or professional installer.

Vehicle Fitment

  • 2018 Ford Mustang GT Coupe 5.0L V8 with Factory Active Performance Exhaust
  • 2018 Ford Mustang GT Convertible 5.0L V8 with Factory Active Performance Exhaust
  • 2019 Ford Mustang GT Coupe 5.0L V8 with Factory Active Performance Exhaust
  • 2019 Ford Mustang GT Convertible 5.0L V8 with Factory Active Performance Exhaust
  • 2020 Ford Mustang GT Coupe 5.0L V8 with Factory Active Performance Exhaust
  • 2020 Ford Mustang GT Convertible 5.0L V8 with Factory Active Performance Exhaust
  • 2021 Ford Mustang GT Coupe 5.0L V8 with Factory Active Performance Exhaust
  • 2021 Ford Mustang GT Convertible 5.0L V8 with Factory Active Performance Exhaust
  • 2022 Ford Mustang GT Coupe 5.0L V8 with Factory Active Performance Exhaust
  • 2022 Ford Mustang GT Convertible 5.0L V8 with Factory Active Performance Exhaust
  • 2023 Ford Mustang GT Coupe 5.0L V8 with Factory Active Performance Exhaust
  • 2023 Ford Mustang GT Convertible 5.0L V8 with Factory Active Performance Exhaust

If there are any questions about this product or if a product description inaccuracy needs to be reported, please contact the MPT Performance experts at (407) 636-7077 or by email for assistance.

Shipping & Returns

Shipping Policy

MPT is proud to offer free shipping on most orders over $149.

  • Free shipping applies only to the contiguous United States. Shipping and handling charges will apply to orders outside the contiguous US, and the buyer is responsible for any duty fees or taxes their home country may charge to import goods.
  • With free shipping, we will choose the best shipping method for your order. We use all major carriers, including USPS, FedEx, UPS, and DHL.

Turnaround Times:

  • MPT Tunes have a standard turnaround time of 2-3 business days, beginning once we receive your MPT Tune Form.
  • We do not process orders on weekends or observed holidays, which do not count as business days.
  • Physical items that are in stock at MPT and ordered by 4PM EST will be shipped the same day. Orders placed after 4PM EST will be processed on the following business day.

Special Considerations:

  • Items not stocked at our location will follow the same processing times but may experience lead-time delays and could incur additional charges. Shipping methods may vary for these items based on what was paid and the requested delivery speed. If you need an item by a specific deadline, please contact an MPT Expert.
  • SCT Tuner Orders with the Prioritized Order option must have their tune forms submitted by 3PM EST to be completed the same day. Forms submitted after this time will be processed the next business day.
  • Orders will ship to the billing address listed on your order. If paying by credit or debit card, we can only ship to the billing address. Contact an MPT Expert for assistance if you need a different shipping address.

MPT Performance Returns and Refund Policy

A Return Authorization Number is required for all returns. Please contact an MPT Expert to obtain an RA # before sending anything back to us for any reason.

MPT tuning charges and license fees are Non-Refundable. The sale is final when MPT has sent the tune file over email. This includes both new tune purchases and tune updates.

Products other than MPT tunes, digital products, and MPT decals may be returned within 30 days for any reason, provided that the product has not been installed and is in brand new, unused condition with the original packaging. Once a product has been installed it is non-refundable. We reserve the right to deny the return, should the product be received and it display signs of installation or unmentioned damage.

For vehicle programmers/tuners, the vehicle must be returned to stock if a program was installed. If a tuning device is returned and has not been returned to stock, a refund will not be issued, and your tuner will not be sent back without a shipping and handling fee.

The customer is responsible for all shipping charges incurred during the return process.

Amount Refunded:
•Returns post marked before 30 days from the date the item was received will be refunded the purchase price, minus a 25% restocking fee and the cost of shipping.
•After 30 days, all sales are Final.
•Shipping charges along with any package insurance are non-refundable. If your purchase was shipped with our Free Shipping option, the cost of the shipping will be subtracted from the total refund amount.

HP Tuners Credits are assigned to the HP Tuners product with the submitted serial number and cannot be transferred. Once you load a tune to your vehicle with the RTD, these credits are Non-Refundable.

Digital products and files that have no ability to be taken back physically, such as an SCT Tuner Unlock, are Non-Refundable.

nGauge Tune License Fee is included in your initial purchase of MPT tunes for the nGauge. This fee is factored into the price of the tunes and becomes Non-Refundable when the stock file has been emailed to MPT.

MPT Decals are Non-Refundable, once they have been received by the customer.

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