I presume by 'thin' you are referring to depth of colour. True cabernet sauvignon is deeply red, so I wonder how much 'varietal' concentrate is in there! Having noted that the Kenridge barolo (although not their cab sauv) includes a small pack of dried elderberries, I added some to a Winebuddy, (along with red grape juice and raspberries, which in themselves wouldn't significantly alter the colour, but add body and flavour). Instructions for barolo are to add berries at start. They sink and so are removed on first racking. However, colour extraction is more effective in the presence of alcohol (as per sloe gin), so adding them later makes more sense.
The Lalvin yeast is not usually 'volcanic', which suggests a rather high proportion of invert sugar, which would be consistent with thin colour.
Cab sauv is aged in oak, so I will add some too. I used them in the Cellar 7 version, which also doesn't include them, although the Winebuddy does, as does the California Connosseur and Kenridge. I've had a 20 litre oak barrel on order for 2 months, but still waiting. My old one is exhausted and imparts no flavour, so I put a handful of toasted oak 'beans' inside with the wine and after just 2 weeks the effect is noticeable. So this time, I will do the same using 5 litre PET bottles, which like wood, are gas permeable, at the maturing, rather than fermenting stage for up to 3 months. I can leave 1 gallon unoaked, to see if it makes any difference with this kit.
I notice the price has jumped to £37, but the Chilean still a very good deal.
Cab sauv is often blended with merlot, something else I intend to try.