The CTS B9 A4/A5/ALLROAD 1.8T&2.0T high flow cat is the premier high flow cat for your Audi A4/A5/ALLROAD 1.8T & 2.0T. Our high flow cat is designed to seamlessly fit in place of your restrictive stock catalytic converter; which is situated immediately after the turbocharger. We have redesigned our test pipe and high flow cat to both retain the same exterior shape and design for customers wanting to have a stealthy test pipe install. Our high flow cat features 3″ stainless steel piping; one 02 sensor bung. Substantial power gains; improved exhaust flow and a more throaty sound are the main benefits from installing our high flow cat. Upon inspection you will notice a flare which is nearly 4″; this flare then tapers to 3″ and is designed to allow for optimal flow as the exhaust gas transitions from the turbocharger to the high flow cat. In addition to being one of the best bang for the buck performance upgrades for B9 owners our high flow cat is also very attractive piece. Each 3″ test pipe is hand tig welded. \n \nProduct Details: \n– T304 stainless steel construction \n– Fully tig welded design \n– Throaty sound \n– Great power upgrade \n \nTo remove the CEL that will occur; proper tuning software must be used. \n \nUse of stage 2 software upgrade is strongly recommended.