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How to Install Flowmaster Outlaw Series Axle-Back Exhaust (15-17 GT) on your Ford Mustang

Installation Time

1 hours

Tools Required
  • Socket Wrench
  • 13mm Socket
  • Reciprocating Saw
  • Penetrating Liquid (to make bolts easier to remove)
American Muscle
Shop Parts in this Guide


1) Begin by measuring 2 ½” beginning from the straight area and mark on both pipes. 

2) Support the exhaust system both in front and behind the area to be cut and then cut both pipes at the marks. Note: Use caution when cutting in order to not damage the gas tank (two black plastic covers).  

3) Using a 13mm wrench, unbolt the two hangers just behind the rear differential from the cross member. Carefully lower the stand under each muffler and slide the muffler assembly forward and out of the rear hanger mount leaving the two hangers attached. 

4) Deburr the end of the pipes where cut with a file or die grinder.

5) Remove the two hanger mounts at the rear of the vehicle from the frame using a 13mm wrench, as you remove them place them with the factory muffler from the corresponding side. 


1) Place the new Flowmaster muffler units next to the factory units and swap the front and rear hanger mounts from the stock mufflers to the new exhaust. Loosely place the provided clamps onto the inlet of each assembly. 

2) Place the right muffler up into position and slide the inlet completely onto the factory pipe. Support the assembly with a stand and remount the rear hanger mount to the frame and tighten securely. Remount the front hanger to the cross member and tighten securely. Repeat this step with the left side. 

3) Adjust and level the two muffler assemblies. A minimum of 1/2” clearance around all parts of the system must be maintained. After adjustments have been made, securely tighten the two muffler inlet clamps. Note: A 1” weld is recommended on each inlet connection. 

This Installation Guide was Written by an AmericanMuscle Customer on 11/13/2017

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