How to Install Corsa Xtreme 3 in. Cat-Back Exhaust on your Mustang

CORSA recommends that the installation of this system be performed by a qualified service center or professional muffler installer who has the necessary equipment, tools and experienced personnel. However, if you decide to perform this install, the use of a hoist and an additional person will be required. 

CAUTION: Never work on a hot exhaust system. Allow time for the vehicle to cool. Always wear eye protection when working under a vehicle. 

Please confirm that all parts are present before beginning the factory exhaust system removal and CORSA exhaust system installation. 

1. Using a clip removal tool or a flat head screw driver remove the six plastic clips holding the rear diffuser to the bottom of the rear bumper. (Fig. A) Using a 13mm socket and 3/8” drive ratchet, remove the two bolts located on the bottom of the diffuser. Remove the second pair of bolts at the axle pipe hanger grommets. (Fig. B) Lastly, remove the two Christmas tree connectors at the rear of the diffuser and remove the diffuser from the vehicle. Place the diffuser and hardware in a safe location as it will be reused during the installation of the Corsa Performance cat-back exhaust system.  

2. Unplug both the driver and passenger side rear exhaust valve actuators by sliding the red plastic clip on the plug away from the actuator. Once the clip is slid back, push down on the plug tab and pull the plug off the actuator. (Fig. C)  

3. Using a 3/8” drive ratchet and 15mm deep socket, loosen the two sleeve clamps at the cat-back connection point. Both nuts must be loosened in order for the clamp to fully disengage. (Fig. D)  

4. Using the 3/8” drive ratchet and 13mm socket, remove the bolt holding down the driver side hanger grommet assembly. (Fig. E) Once the bolt is removed, push up slightly on the exhaust and slide the hanger grommet assembly rearward to free it from the rear suspension sub-frame. Rotate the hanger grommet assembly a minimum of 90° so that it will not interfere with the rear suspension sub-frame. Place the bolt in a safe location as it will be reused during the installation of the Corsa cat back exhaust system. Repeat this process for the passenger side hanger grommet assembly.  

5. Slide the stock exhaust assembly rearward until the stock resonator inlet pipes are free of the sleeve clamps. Lower the front of the exhaust in order to create clearance between the resonator inlet pipes and the sleeve clamps, then slide the complete exhaust forward to remove the rear muffler driver and passenger side hangers from their respective hanger grommets. The stock exhaust assembly will now be free from the vehicle.  NOTE: The use of a soap and water solution may aid in the removal of hanger grommets.  

6. Remove both the driver and passenger side hanger grommet assemblies from the axle pipe hangers using grommet pullers or a similar device. Set the hanger grommet assemblies aside, in a safe location, as they will be re-used for the installation of the Corsa cat back exhaust system. (Fig. F)  

7. Using an 8mm socket and ¼” drive ratchet, remove the three nuts holding down the driver and passenger side valve actuators. Lift the actuators over the studs and place them in a safe location as they will be reused during the Corsa Performance cat-back exhaust installation process. This concludes the factory exhaust system removal.  

NOTE: The use of a soap and water solution may aid in the removal of hanger grommets. 

NOTE: Apply the anti-seize lubricant (supplied) to the threads ONLY of all the clamps and flange bolts. Failure to follow this procedure can cause nuts to seize on clamps and potentially destroy threads. After applying anti-seize lubricant, be sure to thoroughly clean your hands, as lubricant will tarnish stainless steel. All clamps should be tightened using a properly calibrated Torque Wrench. Using an air impact gun will damage the clamp and reduce its ability to effectively seal the joint. It may also cause the joint to separate, thereby causing damage to your exhaust system and to your vehicle. 

NOTE: Align all clamps so that the center of the clamp bolt is 90 degrees from the notch in the pipe. (See Fig. CLAMP) 

1. Remove all exhaust system components from the shipping boxes, including clamps and hardware.  

2. Locate the valve actuator relocation brackets along with the valve actuators and hardware removed during step #7 of the stock exhaust removal instructions. (Fig. G.) Install the actuator onto the bracket and tighten down using an 8mm socket and 1/4” drive ratchet reusing the original hardware. The spring on the actuator should wrap around the larger center pin on the bracket. (Fig. H)  

3. Starting on the driver side, using a 13mm socket and 3/8” drive ratchet remove the top bolt securing the rear most hanger bracket located just above the tip bezels. Next, mount the relocation bracket to the hanger grommet assembly using the top hole. (Fig. I) Confirm the clearances between the valve actuator bracket and the vehicle chassis and tighten down the bolt. Connect the harness to the valve actuator and slide the red clip on the harness plug to secure the connection.  

NOTE: The stock valve actuators must be attached to the valve relocation bracket and the harness must be plugged into the actuator in order to maintain driving mode functionality.  

4. Repeat step #3 for the passenger side. The valve bracket assembly will be rotated and flip 180° relative to the driver side orientation. In this orientation, use the top hole on the bracket assembly when mounting to the vehicle chassis.  

5. Locate the two x-pipe inlet adapters. Slide the adapters into the factory sleeve clamps, and tighten the clamps using the ratchet and 15mm deep socket, until the adapters are snug in the clamps. (Fig. J)  

6. Locate the double helixx x-pipe and two 3” clamps. Install the clamps on the driver and passenger x-pipe inlets so that the bolt is vertical with the nut towards the ground and the bolts towards the outside of the vehicle. (Fig. K) Slide the x-pipe inlets over the x-pipe adapter outlets. Position the x-pipe so that the x-pipe cross-brace located at the rear of the x-pipe is facing down and is parallel with the ground, and the x-pipe outlets are centered around the rear differential. Tighten the clamps using the ratchet and 15mm deep socket until the x-pipe is snug on the adapters. (Fig. L) Place a jack stand or similar device under the x-pipe for support. (Fig. M)  

7. Locate the passenger side hanger grommet assembly removed during step #6 of the stock exhaust removal process. Install the hanger grommet assembly onto the axle pipe hanger in the same position as previously installed on the stock exhaust. (Fig. N)  

8. Locate the passenger side rear muffler assembly, the passenger side axle pipe assembly and two 3” clamp. Install the clamp over the expanded end of the rear muffler assembly so that the bolt is vertical with the nut towards the ground and the bolt is towards the muffler outlet. Next, insert the axle pipe outlet into the expanded end of the rear muffler assembly so that the hanger is towards the top. The second straight of the axle pipe should be in plane with the rear muffler. (Fig. O) Using a 15mm socket and 3/8” drive ratchet, snug the clamp. Do not fully tighten. Install the second clamp on the expanded end of the axle pipe so that the bolt is vertical with the nut towards the ground and the bolt is towards the inside of the vehicle.  

9. Install the passenger muffler assembly and clamped on axle pipe by sliding the rear muffler hanger into the rear hanger grommet located on the vehicle above and just inside of the passenger side bezel. (Fig. P) Next, slide the axle inlet pipe into the passenger side x-pipe outlet. (Fig. Q)  

NOTE: The use of a soap and water solution may aid in the installation of hanger grommets.  

10. Locate the 13mm bolt removed during step #4 of the stock exhaust removal process. Install the front passenger hanger grommet assembly onto the rear suspension sub-frame and tighten it down with the 13mm bolt, using the 3/8” ratchet and 13mm socket. (Fig. R)  

11. Tighten the clamp connecting the passenger muffler inlet pipe to the passenger side x-pipe outlet using the ratchet and 15mm deep socket until muffler assembly is snug on the x-pipe. (Fig. S)  

12. Repeat steps #7-#11 on the driver side of the vehicle. Once the system is secure, it is safe to remove the jack stand from beneath the x-pipe.  

13. Adjust the system accordingly, including the adapter overlap on the stock sleeve clamps, the axle pipe depth and rotation, and the rear muffler depth and rotation. Loosen both the x-pipe to axle pipe connection clamp and the axle pipe to rear muffler connection clamp. Adjust and hold the axle pipe and rear muffler in position while tightening the clamps. Check the position of all hangers to make sure they are properly seated within their corresponding grommets. Check clearances between the system components and chassis. At this time, tighten all clamps to 45ft-lbs using the torque wrench and 15mm socket.  

14. Locate the rear diffuser and stock hardware removed during step #1 of the stock removal instructions. Position the rear diffuser and reinstall all the push pins. Next, using a 13mm socket and 3/8” drive ratchet, install and tighten the two bolts at the axle pipe hanger grommets and the two bolts near the rear bumper connection. (Fig. T) This concludes the installation of your Corsa Performance exhaust system. (Fig. U)  

NOTE: During cold weather start-ups, you may experience an exhaust sound that is deeper and louder in tone than usual. This is temporary and will diminish to normal levels once your engine has reached its normal operating temperature.  

NOTE: Immediately following the installation of your exhaust system, you may experience a trace of smoke after initial start-up. DO NOT be alarmed. The smoke is caused by the burning of a small amount of forming oil residue used in the manufacturing process.