I have a 2004 CTS with Sports/Luxury Package with stock 17" rims. It has a very stiff ride. On rough roads, it pretty much sucks. I'm taking it in to Cadillac next week to have it checked. I haven't heard of anyone complaining about the ride quality of CTS's with the sports package. I have owned a couple of Corvettes which I fully expected to ride rough but I didn't expect a non CTS-V model to rival that ride. Any complaints about ride quality? I know suspension has to be stiff for performance reasons. I'd like to put on 18" or larger rims but I'm afraid that will just make the ride suck that much more.