I saw a two into one cutout exhaust on a v in the cad faq forum and this setup seems like the cat's ***. Hypothetically it seems as it would perform as good as a performance system and only bark on demand (stealth = good in my book). If I am missing a detail or two please chime in.
Cutouts tend to leak and with the CTS-V climate control system I think all of those exhaust gases would be sucked right into the cabin. On paper, cutouts seem like the best thing ever, but in reality they are never as efficient as you'd like them to be.