If you own a Jeep with a 4.0L engine, chances are pretty good that you either have, or will have, a cracked exhaust manifold. Oft-cited causes range from bad motor mounts to poor factoryprocesses.

With suspension and big tires in place on a 4x4, available horsepower and torque begin to wane. While lower axle gears will help restore some of the lost engine performance, many simply get used to ...