How to Install a Stainless Works Long Tube Headers and Catted X-Pipe Kit on Your 2011-2014 Mustang

INSTALLATION INSTRUCTIONS FOR 2013 SHELBY GT500 
CATBACK - P/N M13GT/ M14GT

Thanks for purchasing a Stainless Works Catback for your 2013 Shelby GT500. We 
have gone to great pains to make sure that our exhaust systems fit and sound great. 
Please follow these steps to ensure that your installation goes as planned. 

1.  Stainless Works recommends the use of Hi-Temp RTV sensor safe silicon gasket 
maker as an option to or in conjunction with the use of factory gaskets. The 
recommended Oxygen Sensor Safe RTV is either Valco All-in-One Aluminum or 
Permatex Copper P/N 101BR available at NAPA, Autozone  and other retailers.

2.  Disconnect the battery before starting work on the exhaust system for your 
vehicle. Reconnect the battery when the job is completed.

3.  Your exhaust system can be installed by a weekend warrior but the use of a lift is 
recommended for ease of installation. If using a jack, the vehicle must be placed on a level hard surface and jack stands are required for safety reasons.

4.  You will assemble the components together as specified below, but only snug the 
clamps as you move along from front to back. When placing the X-pipe into position, make certain that you push it fully forward and level it in with the vehicle. After aligning all the components in the vehicle, you will tighten all the clamps working from front to back of the vehicle.

5.  Disconnect battery.

6.  Raise and support vehicle.

7.  Loosen clamps at mufflers.

8.  Loosen double clamps at factory connection point and remove tail pipes saving 
double clamps for installation.

9.  Remove mufflers.

10. Install retro chambered dimpled mufflers using double clamps from factory 
exhaust. 

11. Remove (2) 10mm bolts on driver side cross bar and move it down out of the 
way.

12. Install front and rear tail pipes using 3” clamps. After getting tail over the axle, 
reinstall cross bar using (2) 10mm bolts.

13. Remove front muffler hangers, (3) 8 mm bolts on driver side and (2) 8 mm bolts 
on passenger side.

14. Slide Y-pipe assemblies onto tail pipes using (2) 3” clamps and reinstall factory 
hangers. 

15. Install rear rubber hangers to Y-pipe assemblies.

16. Adjust and tighten all clamps.

17. Be sure to have adequate clearance around all wires, hoses and lines. If anything 
is in contact with the exhaust system, it will melt. Make sure to have at least ½” of clearance and wrap any suspect areas with DEI thermal barrier wrap.

18. Lower vehicle and reconnect battery. 

19. After double checking for clearance and making sure all lines, wires and hoses are 
secured, drive the car for 10-20 miles and re-check all clamps and clearances. Your system may be tack welded at the joints/ clamps to reduce shifting of the system during heating and cooling cycles. Make certain to disconnect the battery before performing any welding.