If you're on a quest for the black stuff, I can only tell you that colonics really really really work.

If you're having 3-4 BM a day, you're in great shape. I fasted for 8 days (nothing like your fast, I'm full of admiration!) I was really hoping to see some gunk myself. Didn't get anything, and after I broke the fast, I was really plugged up.

Now, I just finished my third colonic in three weeks and I feel amazing. After the second one, I started to have the BM corresponding with eating a meal, just like you are now. That's the sign of a healthy lower intestine.

If you really want to get out anything that's in there, a professionally administered colonic will do the trick. I didn't find it a pleasant experience, though I saw a great therapist who only charged 35 bucks. But I feel really cleaned out.