Borla exhaust: Stock dual exhaust's on these motors sound pretty good. GM likes to make there V-6's sound like V-8's. Borla is the only company right now that makes a cat back exhaust system for the 3.4. But that's ok because Borla is a world renowned exhaust manufacturer that uses aircraft grade stainless steel to make there systems. You really can't get any better then that. And it sounds VERY good. Borla part number is 14782. The exhaust can be ordered from RKSport at 1-800-214-8030. Cost on this product is $650.00 ONLY if you mention "Performance Z34" when you order. Otherwiese the regular cost is $800.00. Information about the product can be found at http://www.borla.com. By reducing backpressure from stock exhausts this exhaust will create 12HP more.