CB Engineering - 2014-2016 Jeep Grand Cherokee WK2 EcoDiesel Stainless Steel Dual Cat Back Exhaust. Our cat back exhaust replaces the stock 2" restrictive exhaust with a higher flowing 2.5" cat back exhaust. Our kit uses only 304 Stainlees Steel material. The tubing and all brackets/hardware are all 304 SS. This exhaust gives the Jeep a nice smooth rumble compared to stock. The exhaust tips are 4" polished tips. This bolts in just like stock and mates up to the stock exhaust or our off road pipe.