Conversion Headers
for the
GM Generation III & IV Small Block V8
in
XJ & MJ Jeeps

Kit contents:
- Headers, left & right
- Header flange bolts
- Collector flange rings
- Collector flanges
The GM LS V8 engines are the prime engine for the Cherokee Jeeps. Designing exhaust headers to fit just right into the Cherokee & Comanche Jeeps was tough, but the result is spot on.
The header starts with a generous, 3/8" thick manifold flange. A patented port-seal surface is face ground at the mounting face of the engine head such that they can be used without a gasket (see installation notes below for more information). Headers feature 1-1/2" primary tubes with a 2-1/2" three-bolt style collector.
Coated or Natural Steel
The basic header is offered in natural steel, which the customer can optionally have finished in a variety of hi-temp enamels or other finishes that will offer rust protection and good appearance.
The best thermal and corrosion protection for your headers is our Aluminized Ceramic Coating. This finish offers the added benefit of lower under-hood temperatures and the highest level of protection to the header.
Compatible Engines
These headers are compatible with Gen III & IV GM V8 engines, this includes both the LS and Vortec engines starting with the LS1 in 1997. Truck Vortec series started in 1999. If your exhaust ports are paired in the center these will NOT fit and you likely have a Gen I or II engine needing these headers. While the headers themselves will fit a Vortec style engine with the tall truck intake, the intake manifold and brackets will not fit in your Cherokee without using the lower LS intake and front accessories. See below for links to valuable information.
Compatible Jeeps
These headers are designed specifically for conversions in the XJ / MJ chassis only. They may work in other installation situations, as determined by the installer, but for all other known Jeep LS installs, we recommend these headers.

The driver's side header on an engine that's headed for its home in a Cherokee.

The passenger side of our header kit is more swept back, to put the primary pipe in the provided nook between the unibody and the firewall.

Warning on 4L80E installations in XJ Jeeps:
the extended flange of the transmission case will interfere somewhat with the flange of the Novak headers. While we think the 4L80 is a terrific transmission, it's overkill for just about every Cherokee out there - a 4L60 is usually a better option.
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Installation Requirements
Recommended installation to the engine is high temperature RTV such as Ultra Black® without a gasket. We have found this works exceptionally well. Some have used the original equipment type MLS (multi-layer steel) gaskets with good success. Collector gaskets and bolts are not included with the headers. We recommend using solid copper gaskets to avoid blowouts at that joint. Instructions are provided with the headers.
The short, block-hugging design allows the installer to have the exhaust routed in one of the following three popular ways:
- One circuit under the oil pan, just in front of the sump merging into the opposite circuit which is typically run rearward on the side of the Jeep opposite that of the drop of its transfer case.
- As above, but under the bellhousing slope.
- As above, but behind the transfer case. Then, the exhaust tailpipe can exit the Jeep on either the driver's or passenger's side.

This is one of our prefered exhaust routing jobs on an XJ. It's tight, but it works great.

A macro shot of the above exhaust routing. The 2-into-1 muffler helped make this a clean job. Note that not all emissions jurisdictions may allow for the catalytic converters to be this far from the headers. Do your research.
Also See
- The Novak Guide to the GM Generation III+ V8 Engines
- Gen III+ Engine Parts for Engine Conversions
- The Novak Guide to Jeep Conversion Engine Emissions
- Novak's detailed XJ / MJ conversion instruction package as provided with our engine mounts
- GM Gen. III & IV Small Block V8 Engine Mounts for XJ Cherokee & MJ Comanche Jeeps
- The Novak Guide to Installing Chevrolet & GM Engines into the Jeep XJ Cherokee / Wagoneer & MJ Comanche