I got the Borla dual exhaust cat back system from Quadratec. It didn't make sense to me that JEEP would put a steel exhaust on an off-road vehicle. Cost savings, I guess. The Borla was expensive, but really well made, and easy to install. It's all stainless, too. My gas mileage increased by 3-5 mpg, and supposedly you gain a little hp. I was hoping to gain a little more sound from the exhaust, but its not there.