adding a cup of strong tea 2-3 tbags stewed for at least 5 mins adds tannin to the turbo cider. not sure what it does exactly but its definately beneficial and cheaper than adding tannin powder from hb shops.
i add honey as a fermentable to increase the strength. but it finishes a bit sweeter too and adds a little to the flavour.
Just out of interest, how much honey do you use? I'm about to begin a new batch of TC with 90% AJ and 10% Raspberry Juice (TC comes out nice and sweet) and I'm just wondering how much honey I'd need for a 25 Litre batch, I think I tried one standard jar (300g I think) and I don't think it was enough... cheers.
What kind of yeast do you all use? Can I use the sachet of US-05 or Gervin English Ale Yeast I have lying around? Or do I need some kind of offical 'Trampkiller 2000' extra special turbo cider yeast?
dissolve your honey in some apple juice in a pan on the hob, add it to your concoction and take a hydrometer reading repeat until you get the required strength.
last one i did i used 300g per gallon and it was very very very strong!