1990 Jeep XJ Cherokee - Unleash the Power!

We all know that improving your exhaust system for better flow can help in the horsepower department. In fact, the reason why so many companies like Dynomax have such a wide assortment of upgrades is...they actually work. In our case, the stock '90 XJ with 150,000 miles on the poor 4.0L six-cylinder seemed sluggish and overworked.

Trying to spin the tires in dirt or wet pavement was a joke, so doing a burnout on the street was not going to happen. Sure, we could've spent megabucks on headers, chips, and other assorted stuff--or heck, even swapped in a small-block Chevy--but as this is a daily driver and casual wheeler, reliability is our major concern.

To that end we figured some exhaust upgrades were in order, especially since the catalytic converter had been rattling for a while, and a major blowout in the muffler made the cops eye us like bikers at a beer fest.We trundled down to Magic Muffler & Auto Care Centers in Thousand Oaks, California, where owner John Vasquez suggested the entire Dynomax kit for ease of installation, including a new converter for optimum performance.

But first, we tried our hand at the old beer-can and bandage fix on the muffler to see how well it would work, and to buy us a week or two before we could schedule our rig into the shop. True to hack-job form, we patched the hole and glued it together like any cheapskate would, and wasted our time and money doing it. With that experiment out of the way, Vasquez installed the new Dynomax parts in less than an hour, and we could smoke the tires once again after we unleashed the power. Check out how easy it is to bolt on stuff and gain lost power.

Cheapskate Hack Job
Trying to just get by often means throwing good money after bad. In other words, we figured we could patch the hole in the muffler, since many products are sold to do just that. But when you figure the combination of heat, exhaust pressure, and mechanical movement on the exhaust system, you might as well just forget it. But we had to try, so we went to the local parts store and picked up the muffler repair stuff off the shelf. We followed directions exactly and used the metal can the stuff came in as an extra heat shield.

After soaking the bandage and wrapping the mess up, we let it dry during lunch. That's when Vasquez pulled out his classic collection of things people have tried to fix, like this Bud Light muffler patch, which was secured with a top-quality coat hanger. The Bud patch didn't work very well, and once we fired up the Cherokee the bandage was blown out within a matter of minutes. We didn't want to say we told you so without trying it ourselves, but, we told you so.