I have a 2006 Impala with the 3.9l engine with dual exhaust. I returned it to the dealer due to loud exhaust and the dealer told me that both mufflers were split down the middle and to replace both would cost $806.00! I thought they should be replaced under warranty. They are made from stainless steel. Splittiung indicates defect.
Why don't you show muffler replacement for the 2006 Impala? on 2006 Chevrolet Impala
Unfortunately I had the same problem. The mufflers are not SS. THis is the first car of mine in the last 12 years that doesn't have SS mufflers. The entire exhaust system is mild steel. GM is going the cheap route. Get Walker quiet flow mufflers ate Autozone and have them replaced at a smaller shop because they need to be welded in. I had about $500 in the entire job.