Titanium would be great, but worth more than the NADA value of the car. Akrapovic comes to mind.... $10K for a full system

The early VT series Dynomax mufflers apparently had rattling issues... the latest batch (post November 2010) has the issue resolved. It was all the fault of the supplier of the valves... different supplier = no more noise.

Someone's mission, if they choose to accept it, is to source us a part number for the CTS-V Coupe exhaust tip.