How to Install Pypes Off-Road Cat Delete Pipes - Stainless Steel on your 2011-2014 GT, Boss Mustang

Catalytic converter nuts 35 lb-ft 

Before installation the original catalytic converts looked like this: 

There are two nuts that need to be removed at the front end of each catalytic converter and one on each catalytic converter at the back on the band clamp. The front nut on the passenger side towards the outside of the car is the killer. Once you get this nut off, all the rest will be a breeze. Before I started this project. 

1. I used PB Blaster and soaked all 6 fasteners that need to be removed. Put the vehicle on a lift and raise it to the height you want to work on exhaust. Start with the hardest one, that is my recommendation. 

The nut you want to start with is on the opposite side of the one shown in the picture. I was not able to get a picture of it because of how hard it is to get to. I used a deep well 15mm socket followed by a 3/8' swivel and extensions to make the entire length 39". 

The picture above shows the extension I used to get the first bolt off. 

2. Put the 6' step ladder in front of the car. Climb up on the ladder to push the socket and extension down to the passenger side catalytic converter fastener. Your buddy will need to be underneath the car to help align the socket with the nut on the catalytic converter. Once you get the socket completely on the nut, lower the car to the ground. Have your buddy help hold the extensions straight. This nut will be very tight and rusted on. The car I worked on approximately 43,000 miles. I had to put a cheater bar on the 3/8" ratchet to get enough leverage to turn the bolt. Unfortunately, it turned very hard the entire way off. After you get this nut off, the rest is a much easier and can all be done from underneath the car. 

3. I used a 3/8" swivel ratchet, a 15mm socket and a cheater bar to get the remaining nuts off. They can all be taken off from the bottom. 

The three remaining nuts are shown below: 

After you get the four nuts off the front of the catalytic converters, it is a good time to remove the 02 sensors. 

02 sensors shown above. There is one on each side. 

4. First you need to disconnect the wires that are connected to the 02 sensors. Follow the wires from each sensor to a connector that is supported by the transmission. There is a tab that you need to depress with your fingers and the connector will easily separate. Location is shown below. There is one on each side. 

This is a picture of the plastic connector after it is removed from the car. You can see the tab that needs to be depressed to disconnect the plug. 

5. Now it is time to unscrew the 02 sensors. I used a 7/8" open end wrench, but they make a special socket that can be used to remove them. The ones on my car were not that tight and I easily removed them with a 7/8" open end wrench. 

The pictures above show both of the 02 sensors removed from the catalytic converter. 

6. Each side has one remaining bolt that needs to be removed. There is a band clamp at the end of each catalytic converter. Before removing these I recommend getting a long plastic tie and supporting the exhaust from the driveshaft directly above the Y pipe. The location for the support is shown below: 

7. After supporting the exhaust, remove the two remaining nuts on the band clamps. 

8. I used a 13mm socket and rachet to loosen these bolts. After you loosen the band clamps, slide them to the rear as shown below. 

9. At this point you can pull each catalytic converter back towards the rear of the car and they will come off. 

Installation of the new cat delete pipes is significantly easier than the removal of the original catalytic converters. The new cat delete pipes do not come with new exhaust gaskets. I considered replacing them until I found out that they are approximately $27 each. I reused the existing gaskets. I took the new bolts that came with the cat delete pipes to the hardware store and bought stainless steel bolts the same size. If you ever have to remove them, you will be glad you used stainless steel. I recommend starting with the hardest one. Because the pipes are much smaller in diameter than the catalytic converters, you can put in and tighten all the fasteners from underneath. Mine were 15mm bolts and nuts. 

10. Put the passenger pipe in place with the existing gaskets and tighten the bolts to 35 lb-ft. Do the same on the driver side. 

11. Now push the exhaust back in place. 

12. Once the exhaust is pushed together, tighten the band clamp bolts shown below. No torque specification is provided. Just don't break the bolt. 

13. Time to reinstall the 02 sensors. I recommend putting anti-seize on the threads before putting them back in to ensure that they can be removed again. Put a small amount of anti-seize and screw the 02 sensors back in. 02 sensors shown below. 

13. Reconnect the two plastic clips, one on each side. They just push back together. You should feel or hear a click when they are properly connected. 

When you are done the new cat delete pipes will look like this: 

Good job, you are done. Lower the car, start it up and you will DEFINITELY hear a difference. 

Installation instructions written by AmericanMuscle customer, Brent Rowse, on 8/11/2015.