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How to Install Corsa 3 in. Touring Cat-Back Exhaust w/ Polished Tips - Split Rear Exit (09-13 4.8L Sierra 1500) on your GMC Sierra

Tools Required
  • Tape measure
  • Black marking pen
  • 13mm, 15mm socket and ratchet
  • 1/2" socket
  • Chain style pipe cutter
  • Grommet pullers
  • Soapy water
  • Safety glasses
  • Torque Wrench
American Muscle
Shop Parts in this Guide

Please take time to read and understand these installation instructions.

CORSA recommends that 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. 

Removal of Stock System:

1) Scribe a line 12" forward from the front face of the stock muffler. (See Fig. A)  

2) Place a chain style cutter around the exhaust pipe at the scribe line location and cut the exhaust pipe. (See Fig. B)  

3) Remove the hangers from the grommets at the muffler exit, near the spare tire and finally ahead of the muffler, using grommet pullers or similar device. (See Fig's C, D & E)  Note: Using a soapy solution on the grommet hole will make the job easier.  

4) Use a 13mm socket to loosen spherical clamp and remove factory headpipe. (See Fig. F)  

5) Remove the muffler and rear tailpipe section from the vehicle by lifting the tailpipe over the rear axle and pulling forwards toward the front of the vehicle. (See Fig's G & H)      

Installation of CORSA Exhaust System:

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 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 your vehicle. 

1) Locate the CORSA Head Pipe assembly and slide the spherical joint onto the factory pipe. Reuse the factory spherical clamp and loosely snug the spherical joint. Insert the hanger into the factory grommet. (See Fig. H)  Note: Using a soapy solution on the grommet hole will make the job easier. 

2) Slide a supplied 3" TORCA clamp over the inlet of the CORSA muffler. Make sure the weep hole is facing down then slide the muffler onto the Head Pipe and pre-tighten the clamp so it is snug but can still rotate. (See Fig's I, J and K)  

3) Slide a supplied 3" TORCA clamp over the inlet of the CORSA Dual "Y" Assembly and insert over the muffler exit and place the hangers into the factory grommets. Pre-tighten the clamp.  (See Fig's L, M, N, & 0) Note: Using a soapy solution on the grommet hole will make the job easier.      

4) Slide a 2.5" TORCA clamp over the passenger side tailpipe assembly and place the pipe onto the upper end of the Dual "Y" Assembly and insert the hanger into the factory grommet. Pre-tighten the clamp at this time. (See Fig's P, Q, R, & S)  Note: Using a soapy solution on the grommet hole will make the job easier.  

5) Slide a 2.5" TORCA clamp over the "Driver over the axle Pipe" and place the pipe onto the lower end of the Dual "Y" Assembly. Leave the pipe loose at this time for adjustment when placing the driver side tailpipe onto the over the axle pipe. (See Fig's T, U, & V)  

6) Locate Driver Side tail pipe hanger assembly ("U" shaped Wire Loop & Plate) and hardware (threaded Mounting Plate, bolt and washers) (See Fig. W). On the driver side of the vehicle, position the threaded rectangular-shaped mounting plate on top of the frame rail over the hole located furthest forward from the rear of the frame rail. (See Fig. X & Y)  

7) Insert the supplied 5/16"-18 bolt through the tail pipe Wire Loop & Plate hanger and thread it into  the threaded Mounting Plate on top of the frame.  Note: Position the driver side hanger so that it faces toward the spare tire (See Fig. Z) 

8) Slide a 2.5" TORCA clamp over the inlet of the drivers side tailpipe and install tail pipe onto the over the axle pipe (See Fig's AA, BB & CC). Insert tail pipe hanger into provided rubber grommet and pre-tighten clamp at this time.  Note: Using a soapy solution on the grommet hole will make the job easier.  

9) Locate exhaust tip assemblies and slide 2.5" TORCA clamp over expanded end of tip assembly. With the bolt and nut facing up, snug fit the clamps on each tip assembly. Do not tighten at this time. (See Fig's DD & EE)  

10) Check the alignment of tail pipes and tips. (See Fig. FF) Make sure there is at least 1.5" clearance between the tips and bottom of the bumper. Align tail pipes if necessary by making adjustments at the slip joints. 

If you have any questions about the installation process, call CORSA Performance and ask one of our Sales & Technical Service Representatives. Do not attempt to make any modifications to parts as this will void your warranty. Call (800) 486-0999. 

NOTE: Failure to follow these instructions and maintain the recommended clearances to the above listed parts could impact the long term performance of said parts. Please contact the CORSA Performance Customer Service Department (800-486-0999) if you have any questions related to the above information. 

11) Starting from the front of the CORSA exhaust system, tighten all spherical clamps to 21 ft-lbs and TORCA clamps to 45 ft-lbs using a torque wrench. Make sure clamps are positioned and tightened as shown. (See Fig. KK)  

12) It is strongly suggested that all clamps be checked and tightened if necessary after road testing the vehicle and after the system has cooled. 

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 CORSA 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. 

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