finally installed my corsa sport exhaust p/n 14925 today after it sat in garage for 2 weeks. drove it around for about an hour and it has a horrible whistle around 4700-4800 rpms. its sounds horrible and it is loud. I am very disappointed after all the money I paid for it . has anyone ever had this problem. only heard of this on some cts-v's with corsa systems. just my luck that they are closed for the holidays so I cant get this resolved soon. btw, truck is 2011 Silverado 5.3. bone stock except for corsa.