Devils in the detail, mate ! Read the smallprint ,if you havent already that is ,and you may find that it says that results of "up to 21%ABV are
possible " .
Well ,I say that ,but I havent looked at every kit on the market or yours specifically .The ones that I
have looked at say that .If you look at the "turbo yeasts" that seem to mainly come out of scandanavia and australia they mostly have a similar caveat .
Having mouthed off like I actually know what I am talking about ,I cant see any reason why you SHOULDNT be able to achieve fine ,high ABV results if you do everything scrupulously .As long as it all goes to plan then its just a case of adding the flavouring and wah-hey ! I have never tried these kits myself but many years ago I DID make some high strength wines to be used as base for liqueurs. Back then there were quite a few flavourings for specific well known brands and some for spirit flavours too .One thing I remember (probably from an old CJJ Berry book - he was my mentor - well ,his books were!) was using capsicum tincture to give a "bite" that made them seem much stronger .I have looked for the tincture all over ,even asked chemists ,but it doesnt seem to be available in the UK anymore.
Having waffled on I havent really answered your question at all !But as you can see, I AM very interested in the subject ,so please keep us updated as to how it pans out......good luck ,mate ! :
shocks