The ultimate engineered power system: adds exhaust manifold to Stinger system, removes more factory restrictions for maximum engine efficiency, power and fuel economy. 4.0L 6-CYL: 1998-06 WRANGLER. PowerPack combines all of Banks' 4.0L Jeep airflow upgrades to maximize power no matter what the terrain. It starts with the free-breathing Banks Ram-Air Intake and high-flow Monster Exhaust, then adds torque-optimizing exhaust manifold (Banks Revolver for 1998-99 models or TorqueTubes for 2003-06). PowerPack unleashes the power your engine wastes trying to overcome factory intake and exhaust airflow restrictions. By improving engine efficiency, more power gets to the rear wheels, your engine lives longer and fuel economy improves. The exhaust note is rich and authoritative, and includes a stainless-steel tailpipe tip in either chrome or black. The included Banks AutoMind programmer comes ready to run with pre-loaded power, with towing, sport, or economy settings right out of the box... and right for the job at hand! Its calibrations were developed with power and increased MPG in mind. The AutoMind can also display a host of critical engine functions and provides service technician diagnostic capabilities with its ability to scan and clear vehicle trouble codes. Gale Banks talks about the exhaust manifolds for 4.0L Jeeps... Banks TorqueTube headers have been the best available power producers for quite a while.;About a year ago, I applied my 5 cylinder collector patent to the '91-99 Jeep 4.0L 6-cylinder header using a firing center tube & I Kicked My Own Ass! The NEW Revolver header matches the low end of the previous TorqueTube design & adds a ton of top end power. Have a look at the wheel dyno results. Above 3400 rpm we've added power so your Jeep marches to the shift with no loss in low end torque. Add a complete Banks PowerPack Bundle & get even more! --Gale Banks