i had runflats on my CTS-V stock. They were extremely loud in the cockpit. The particular version I had didn't last for anything, but I figured that was more related to the high performance aspect.

Responsiveness with non-runflats I replaced them with was at least as good. I had to buy a wheel to throw in the trunk, and five tires, since the cars with runflats don't come with spares. Well worth it to get rid of the runflats.