4 Wheel Drive & Sport Utility October 2003
photography Kevin McNulty
Squeezing more performance out of your Wrangler’s 4.0L I-6 engine is easier than you think, and a good place to start is with your vehicle’s exhaust system. For some reason, auto manufacturers continually overlook the fact that a performance-tuned, free-flowing exhaust system will greatly increase a vehicle’s powerband and fuel efficiency. In a perfect world, vehicle’s would already come with these exhaust systems, but because they don’t, manufacturers such as Gale Banks Engineering consistently step up to the plate, designing systems that will unleash you vehicle’s untapped power.
Banks Engineering has been a leader in the performance exhaust industry since 1958. The company is renowned for its turbo designs, gas and diesel exhaust systems, exhaust braking systems, and the quality engineering that goes to each component. It has recently released its new performance exhaust upgrades for the ’91-03 Jeep 4.0L I-6 engine and Jeep Wrangler exhaust, the TorqueTube Exhaust Manifold Assembly and the Stinger Exhaust System. The TorqueTube Kit is comprised of a stainless-steel header, head pipe (optional), a high-temperature gasket, and hardware. The Stinger kit comes with a stainless-steel, straight-through Dynaflow muffler, a 2-1/2-inch tailpipe, and a stainless turndown tailpipe (exhaust tip). Both kits include all the necessary mounting hardware, the comprehensive installation manuals, and the components carry a limited lifetime warranty. One system can be installed without the other.
The exhaust tubing for both systems is mandrel-bent for a restriction-free flow. Banks’ testing of the Dynaflow muffler has shown a 140 percent increase compared with the OEM muffler. The TorqueTube header is designed to optimize exhaust flow and eliminate the problematic OEM cast manifolds. The stock manifolds don’t align squarely with the exhaust ports, causing flow restrictions. Banks’ 1/2-inch header flange is machined dead flat and precisely fits the port pattern, allowing free flow for escaping exhaust gases. The flange is fully welded to the tubes on both sides to prevent cracking and seperation. Both systems will increase the horsepower and torque of the vehicle.
Wanting to harness every last drop of energy out of our ’01 Wrangler, we let Banks Engineering have the vehicle for the day to install both systems. Within a matter of hours, the restrictive OEM exhaust was swapped out for the Stinger and TorqueTube setup. The most time-consuming part of the install was the removal and installation of the intake manifold assembly. Other than that, every component in the kit fit perfectly – even the rear tail pipe, which sometimes tends to be a problem. The Stinger tailpipe is precisely shaped so that it fits under the track arm bar and makes its way between the right rear damper and fuel tank without any clearance issues. There is more than enough room between these components, even if the axle was fully articulated.
Once the system was installed, we fired the engine and noticed a deep throaty growl that wasn’t overly obnoxious but just right. Even though the Wrangler isn’t known for its quiet ride, a deafening exhaust drone didn’t resonate throughout the interior of the vehicle. While test-driving the TJ on the highway, we immediately noticed the performance gains of increased torque and horsepower compared with the restrictive OEM exhaust system. With the TJ breathing a little easier, we can’t wait to hit the trails.