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How to Install a Quad Tip Axle-Back Exhaust on your 2015 EcoBoost Mustang

Installation Time

1 hours

American Muscle
Shop Parts in this Guide

ROUSH Quad Tip Exhaust Installation Instructions

P/N: 421920 (R1315-5231PV) – Fastback GT V8

421921 (R1315-5231PVCV) – Convertible GT V8

421922 (R1315S1-5231PV) – Fastback EcoBoost I4

421923 (R1315S1-5231PVCV) – Convertible EcoBoost I4

Application: 2015 Ford Mustang

Important Note:

Before installing your ROUSH Performance Product(s), read through the entire installation procedure and check

to make sure all items are present. Contact ROUSH Customer Service at 1-800-59-ROUSH, weekdays from

9:00 AM to 5:00 PM EST, with any questions regarding fit, missing parts or instructions that are unclear to you.

Equipment and Supplies Required

• Exhaust Pipe Cutting Tool

• Tape Measure

• Scissors

• 17 mm Wrench

• Marker

• Deburr Tool

• Drill

• Drill Bits: 1/8", 17/32"

• Corrosion Inhibitor (Motorcraft PMP-19500-6000 Clear Topcoat recommended)

• 3/8" Drive Ratchet

• 3/8" Extension

• 3/8" 13 mm Socket

• 3/8" 15 mm Socket

• 3/8" Torque Wrench

If you are missing any items, please call us toll free at 1-800-59-ROUSH.


The information contained in this publication was accurate and in effect at the time the publication was approved for printing and is subject to change without notice or liability. ROUSH Performance Products (RPP) reserves the right to revise the information presented herein or to discontinue the production of parts described at any time.




Appropriate disassembly, assembly methods and procedures are essential to ensure the personal safety of the individual performing the kit installation. Improper installation due to the failure to correctly follow these instructions could cause personal injury or death. Read each step of the installation manual carefully before starting the installation.

• Always wear safety glasses for eye protection.

• Place ignition switch in the OFF position.

• Always apply the parking brake when working on a vehicle.

• Block the front and rear tire surface to prevent unexpected vehicle movement.

• If working with a lift, always consult vehicle manual for correct lifting specifications.

• Operate the engine only in well-ventilated areas to avoid exposure to carbon monoxide.

• Do not smoke or use flammable items near or around the fuel system.

• Use chemicals and cleaners in well-ventilated areas.

• Batteries produce explosive gases, which can cause personal injury. Therefore, do not allow flames, sparks or flammable substances to come near the battery.

• Keeps hands and any other objects away from the radiator fan blades.

• Keep yourself and your clothing away from moving parts when the engine is running.

• Do not wear loose clothing or jewelry that can get caught in rotating parts or scratch surface finishes.

• Allow the engine, cooling system, brakes and exhaust to cool before working on a vehicle.


Perform this installation on a good clean level surface for maximum safety and with the engine turned off.

Note: For convertible installation ONLY, follow the section below titled “Rear Sub Frame Removal”

Rear Sub Frame Removal

1. Convertible Mustangs have a rear sub frame connector that needs to be removed in order to install the ROUSH exhaust system. In order to do so, remove nine (9) 15 mm bolts and lower the sub frame connector to the ground with the help of an assistant. After removal, follow the remaining steps in the installation guide before finally following the reverse of this step to reinstall the sub frame connector. Torque to 46 lb-ft (63 Nm).

Removing Stock Exhaust

1. Using a suitable exhaust pipe cutting tool, cut completely through the stock exhaust in the two (2) locations shown below.

2. Remove the two (2) 13 mm bolts that retain the exhaust hangers on the IRS sub frame.

3. Unhook each exhaust hanger from the sub frame and remove each muffler assembly by sliding the inlets down and forward to extract the rear exhaust hangers from their mounts.

Quad Tip GT V8 and EcoBoost I4 Exhaust Installation

1. Cut out the drill template that is provided on the last page of this installation manual. Check that it has printed at a 1:1 scale by measuring the distance between the two holes. It should measure exactly 2 inches (50.8 mm).

2. Locate the template onto the rear chassis sub frame as shown in the pictures below and mark the drill holes with a center punch. Use the same template to mark the holes on both the RH and LH sides of the vehicle.

3. Drill all four (4) pilot holes that were marked in the previous step with a 1/8" drill bit followed by a 17/32" drill bit.

4. Deburr the drilled holes and apply automotive clear coat. Install four (4) rivet nuts (P/N: 95105A191) using the supplied bolt and nut from the rivet nut installation kit (P/N: R1315-5231HWK). Insert the nut onto the bolt and thread the bolt into the rivet nut. Hold the nut with a 17 mm wrench and tighten the bolt nut with a 10 mm socket until the rivet nut is fully seated.

5. Install the two (2) supplied exhaust hangers (P/N: 1315-5A261 and 1315-5G298) and four (4) bolts (P/N: W500224) as shown below. Torque to 18 lb-ft (25 Nm).

6. Remove the two (2) IRS sub frame mounted exhaust hangers from the stock exhaust system and slide them onto each side of the ROUSH exhaust.

7. Slide the rubber exhaust isolators (P/N: BR3Z-5A262) onto the rear muffler hangers. Install the block off gaskets (P/N: CV6Z-9450) followed by the block off plates (P/N: 1315-5231BOP) and fi nally the outlet couplers (P/N: 1315-5232CPL and 1315- 5230CPL) onto both of the flanged outlets on the muffler assemblies. Secure the outlet couplers with the four (4) nuts (P/N: NM8X125HF) and torque to 18 lb-ft (25 Nm). Slide the exhaust pipe clamps (P/N: 94-0052) onto each outlet of the forward section of the factory exhaust.

8. Install each side of the ROUSH exhaust system by inserting the rear exhaust hangers first and then sliding each side forward to fully seat the inlets with the forward section of the stock exhaust. Be sure to connect the rubber isolators to the hangers that were installed in step 7 and also reinstall the two (2) IRS sub frame exhaust hangers with the two (2) 13 mm bolts that were removed in step 2 and torque to 18 lb-ft (25 Nm). Torque the exhaust pipe clamps to 35 lb-ft (47 Nm).

9. Slide each exhaust tip (P/N: 1315-AVTIP) onto the muffler outlets with the exhaust tip clamps (P/N: 10-0338). Align the tips to the rear valance. Torque the exhaust tip clamps to 35 lb-ft (47 Nm).

Congratulations!! The installation is complete.

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