Conversion to a Cat-back Exhaust
Cat-back exhausts function like every other exhaust system in that its job is to carry away spent gas fumes from the engine and into the open air. The cat-back difference is that this flow from spent to air vent is larger and has better flow than the factory installed exhausts. If you own a Jeep for very long, it doesn’t take too long to decide that one of the first mods you want to do is to the exhaust system. Keeping the engine clear will improve the performance, save you on gas, and increases the horsepower as well as torque. They do make a little more noise, given their size and increased flow, but there are ways around that. Here’s how to convert from a typical axle back exhaust to a cat-back. You can do this mod on the following Jeep models:
- Wrangler JK, Rubicon, Sahara, Sport, Wrangler Unlimited, and Islanders (2007-2017)
Tools You’ll Need:
- The Cat-Back™ System
- Bosch Rear Exhaust Oxygen Sensor
- Rubber Exhaust Hanger/Insulator (optional if already equipped).
- Safety Glasses
- Direct Fit Catalytic Converter.
- 3/8 Drive Ratchet Wrench.
- Paint Pen
- 9/16" Deep-well Socket
- 1/2" Deep-well Socket
- 22mm O2 Sensor Socket
- 14mm Socket
- Drop Light
- Metal File
- Pair of Jack Stands
- Bright pen light
- Mechanic Gloves
Step One: Use your Jack and place the Jack Stands under the muffler and under the tail pipe.
Step Two: Remove the existing exhaust as well as the piping. This may be difficult if your exhaust is really corroded. If this is the case, you may have to use your Sawzall to get the exhaust components off. Remove the catalytic converter as well.
Step Three: Look at the Cat-back system and locate the inlet and outlet, which will be indicated with an arrow. The side that has the IN on it is the side that will be mounted toward the front of your Jeep. This slips over the front pipe that you cut during removal of the old one. If you put it in correctly, the arrow will point to the rear of the vehicle which indicates which way the exhaust will be flowing.
Step Four: Put the catalytic converter over the cut pipe in front and then fit the pipe clamp over the connected pipes. Don’t tighten them fully just yet, because you may have to do some adjusting.
Step Five: Attach the muffler to the catalytic converter: outlet toward the rear of the Jeep.
Step Six: Find the 2 ½ inch pipe clamp, which has a hanger attached to it and use this to support the rear of the muffler. Use the enclosed rubber insulator and slide the clamp hanger through the lower hole, then let it hang at the rear of the muffler. Don’t both to clamp down the top section right now as you’ll more than likely now must do some adjusting and repositioning of the muffler so that the outlet holes are lined up with the hanger.
Step Seven: Insert the clamp-hanger into the bottom hole of the insulator, then line it up with the muffler outlet hole.
Step Eight: Take a jack stand and put it at the rear of your Jeep to give some additional support to the tailpipe while you work on it. There’s an extreme bend in the tailpipe. Find this and place it over the rear axle, making sure it has enough clearance. Slide the tailpipe over the rear axle so that it rests on the clamp-hanger. This will let you move it around so that you can line up the holes in the muffler. Once the tailpipe and the muffler are mated, slide the jack stand in, then fit the other pipe clamp at the end. Tighten the clamp with the hardware provided.
Step Nine: Inspection time. You should have all of the components connected at this point, but you will have to double check. The best way to do this is to take a very bright light and look at each of the clamping points and will make a good seal. Once you are sure they are all positioned good, with enough overlap at the connections, tighten each clamp so that it slightly indents the metal. Cut off any excess piping, then install the finish tips.
Step Ten: Make sure to reinstall the O2 Sensor on the catalytic converter. You may have to clear the codes on your Jeep’s internal computer so that it will recognize the O2 Sensor and adjust to normal operating conditions. If you don’t have a code reader on hand, just unbolt the negative battery terminal, then reconnect. This should reset it.