Good question...I bought my G8 from Burns on rt 70 and had them do some recall work years ago. I know another member may have brought his car to Kerbeck on 73 in Palmyra. I think your best bet would be Holman Cadillac on 73 in Mt. Laurel just because they still service CTS-V's. However, ultimately I don't have the best answer to your question.
2009 G8 GXP, 6M Sport Red
Kooks 1 7/8" Longtube headers w/ JetHot Silver
Kooks high flow cats
SLP Skip Shift Eliminator
SLP 160* thermostat
Rotofab CAI w/ dry filter
HP Tuned @ Tune Time Performance 394rwhp/385rwtq