Do an internet search on *asparatame toxicity*. It is enlightening. You want to do the Master-Cleanse for what? Cleansing? Then why drink something toxic? {That's the coke I'm talking about.} :)
If you are going for weight loss only, there are MUCH better ways to lose weight that won't have such a bounce back effect after you stop them. Like exercising. If you're doing the Master-Cleanse just for weight loss you may get more support in that forum. I doubt they'll encourage diet coke though.
If you don't like the taste of the lemonade make sure you're mixing it correctly. If it's just the pepper, then use less, the book says *to taste*. Good luck to you. :)