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How to Install a Flowmaster American Thunder Cat Back Exhaust on your 2007-2017 Jeep Wrangler JK

Installation Time

2 hours

Extreme Terrain
Shop Parts in this Guide

Removal:

1) Raise the vehicle up on a hoist or rack to working height. If you do not have access to a hoist or rack, raise the vehicle and support securely with jack stands.

2) Loosen the band clamp on the inlet side of the muffler (left side).

3) Support the muffler with a stand, and separate the two hanger rods from the rubber mounts. Remove the muffler assembly. After removing the muffler assembly, remove the nuts securing the factory rear muffler heat shield. Removing this shield will allow the exit pipe to tuck up tighter to the vehicle.

4) Loosen the band clamp at the rear of the factory Y-pipe and separate the two hangers on the pipe from the rubber mounts on the vehicle. Lower the pipe from the vehicle and set aside. 

Installation:


1) Place a provided clamp onto the slip-fit of inlet pipe assembly #710TBS and slide over the back of the factory Y-pipe. Connect the hanger on the pipe to the rubber mount on the vehicle and tighten the clamp enough to hold, but still allow for adjustment. The hanger closest to the slip-fit is for 07-11 models, the other hanger is for the 2012-2013 model. You may choose to trim off the hanger that is not used. 


2) Place a provided clamp onto the inlet of muffler #12518409-Z and slide over the back of inlet pipe #710TBS. Tighten the clamp enough to hold, but still allow for adjustment. 


3) For 2 Door Model Vehicles you will need to trim 20.50” from the front (long end) of over-axle pipe #86126S. Place a provided clamp onto the outlet of the muffler. Place over-axle pipe assembly #86126S over the rear axle and slide into the muffler outlet. Connect the hanger on the pipe to the rubber mount on the vehicle and tighten the clamp enough to hold, but still allow for adjustment. 


4) Place a provided clamp onto the slip-fit of exit pipe #86127S and slide onto the back of over-axle pipe #86126S. Connect the hanger on the pipe to the rubber mount on the vehicle and tighten the clamp enough to hold, but still allow for adjustment. 

5) Adjust the position of the muffler, pipes and exit pipe to provide a satisfactory fit. Maintain a minimum of 3/4" clearance between the Flowmaster system, the drivetrain and chassis components, while also keeping suspension travel and vibration in mind. Tighten down all clamped connections securely. For a cleaner appearance and more secure installation, we highly recommend welding all slip-fit connections. Install the provided push-on hanger keepers onto the ends of all of the hanger rods to prevent them from slipping out of the rubber hanger mount.

PACKING LIST

Qty  Description  Part #
1  Inlet Pipe Assembly  710TBS
1  Muffler  12518409-Z
1  Over-axle Pipe  86126S
1  Exit Pipe Assembly  86127S
1  Parts kit  PK739
4  2 ½” Clamp  MC250BS
4  1/2” Hanger Keeper  HW503