Poop Reduction Initiative.
Last week we took the cats to our vet for worms shots. We asked the vet, who is a kitty-genius, if worms would cause the kitties to poop and fart extra-stinkily. Ingrid had just invented a new trick where she would cuddle, silently fart, and then run away.
The vet said no, generally that's caused by overeating. He called it a "disease of domestication". He said that his wife often takes in strays, and initially they produce small, tight, non-smelly clumps in the litter box. But after a while of unending kitty kibble buffet, the stools become loose and smelly. He said that overeating pushed the beneficial, but smelly, micro-organisms OUT of the feline digestive system.
Once home, we began a strict regime of feeding the kitties only their alloted amount off the back of the box. Rather than topping off the dry food a few times a day, we give them each 1/2 cup kitty kibble for breakfast, ~2oz wet food after work, and 1/4 cup before bedtime.
The results have been delightful. We're spending less time scooping boxes, and less money on both food and litter. The kitties aren't starving; there's always a little kibble left in their bowls. In fact, they're probably healthier from not grazing all the time.