Scott - Generally, people get (and give) pretty good advice in this group. I have to disagree a bit, though, with the recommendation to use an alternate yeast on a kit. Tim Vandergrift (Tech. Svcs Mgr for Winexpert, and a very knowledgeable guy) has described in other posts some of the issues involved with this. The short version is "kits are different." A specific yeast that works well on freshly-crushed Syrah, for example, may just not work nearly as well on a Syrah kit. Part of the reason is that the concentration of the juice in the kit- making process changes some of the flavors and creates some chemicals in the juice that the yeast need to be able to digest. Some yeasts handle them just fine (e.g., Premier Cuvee). Others do not. Hence, replacing a kit yeast with another yeast, even if that yeast variety is recommended for the particular grape, is a chancy business. Tim has described how his firm tests new kits with many different yeast varieties (dozens, or more) in order to find the best ones. There really is a lot of science, as well as wine-making smarts, that go into kit development. Except in really extraordinary circumstances, following the kit-maker's directions is likely to give you the best result you can get, based on the ingredients you are starting from.
From your posts in other threads, it sounds as though you are trying to produce a seriously tannic Cabernet Sauvignon. That's probably going to be the hardest style or variety to do well from a kit, as tannins just don't survive the kit-making process very well. I think this conclusion is supported by the results (recently issued) of the latest amateur winemaking competition held each year by Winemaking magazine. In virtually every category, kits won far more medals than wines made directly from grapes. The exceptions were Cabernet Sauvignon and Zinfandel, where more medals were awarded to wines made from grapes. In terms of the Gold and Silver medals, Cabernet ran about 2:1 in favor of grapes as compared to kits. To me, the results indicate that, in general, kit-wine quality has improved a lot, to the point where kits compare favorably to wines make directly from grapes, but that there are still a few styles / varieties that just don't work as well with kit technology (yet).
If you do want to pursue a really high-end Cab. from a kit, there were four that received enough medals to stand out from the competition (IMHO, and in no particular order):
Cellar Craft Limited Release Cabernet Quartet (this was a one-time kit; don't know if there are any left in circulation) RJ Spagnols Cellar Classic Winery Series Cabernet Sauvignon RJ Spagnols En Primeur Calfornia Coastal Cabernet Sauvignon Winexpert Selection Estate Series Lodi Ranch 11 Cabernet Sauvignon
I have not made any of these kits, and there are very likely other kits out there that might satisfy you. But these kits did well enough that they seem to me to be promising candidates. You should also plan on aging these wines for at least a year (or two) before you make any final judgments on quality.
Best of luck --
Doug