Cat-back Exhaust (Banks Monster / Magnaflow / Dynomax)
Replaces everything from the cat back to the tailpipe with 2.5" or 3" tubing and a free-flow muffler. Modest power gain, big sound improvement.
The stock 4.0L exhaust pinches down to ~2.25" with a restrictive muffler. A 2.5" mandrel-bent cat-back is the most common upgrade. Banks Monster (PN 51315) is the historical favorite with the matching Banks long-tube; Magnaflow and Dynomax offer similar setups at lower cost. JBA also packages a system. Most kits include muffler, intermediate pipe, tailpipe, and tip.
Real-world gain on a stock engine with the cat-back is 3-5 whp — you mostly buy a deeper exhaust note. Pair it with a long-tube header and you start to see meaningful numbers because the stock cat and muffler choke the header. The XJ exhaust drone with a Magnaflow is moderate; the Dynomax tends to be quieter; Banks is the most aggressive.
Going 3" mandrel (see next entry) only matters if you're stroked or supercharged. On a stock or mild 4.0L, 2.5" is plenty.
Fitment note: the stock setup exits behind the rear tire on the driver side. Most cat-backs preserve this. If you're running a rear bumper with tire carrier or running boards, double-check tailpipe routing before ordering.
Why it works
- better sound
- small gain
- more manageable than header
Trade-offs
- small gain alone
- drone potential
- rust on old hangers
Tools required
- socket set
- sawzall (if cutting OEM)
- exhaust clamps
- jack stands
Parts
| Part | Vendor | Est. price |
|---|---|---|
| Banks Monster cat-back | Banks Power | ~$600 |
| Magnaflow 2.5" cat-back | Magnaflow | ~$450 |
| Dynomax cat-back | Dynomax | ~$320 |
Sources
Related
- Full 3" Mandrel-Bent Exhaust
- Long Tube Header (Banks / Borla / Hedman)
- All Jeep Cherokee XJ guides & tools
- Browse the full DIY database
Written and maintained by an AZ wheeler and driveway wrencher. How we source guides. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.