Meat, organs, bone, and taurine are absolutely essential. All preferably raw; however a cooked diet is better than commercial.
Any supplements you use should be from animal sources e.g. fish oil, and not flax or hemp seed oil for Omega-3.
Meat, organs, and bone contain 0 fiber. On a whole prey diet, cats would ideally consume some fur and feathers. Some fur/feather might need to be trimmed off since some cats' digestive system have trouble with them. Next best choice is to add high-moisture low-glycemic index vegetables @ around 3-5% of your cat's diet. If your cat is allergic to vegetables, then psyllium or rice bran (~ 1/16 - 1/8 teaspoon daily) are okay again depending on how well your cat handles this fiber source.
Avoid grains completely as a large % of cats are allergic to them. At best, grains are an unnecessary source of carbohydrates for cats, these erstwhile capable guardians of ancient Egypt's granaries.
Cats need preformed Vitamin A as they cannot convert beta-carotene into Vitamin A. Interestingly enough, 2 studies have shown that although cats absorb beta-carotene presumably obtaining an anti-oxidant benefit from it. Of course they do not convert it to Vitamin A, so meat and organs should supply cats' vitamin A requirements, not vegetables.
Cats cannot convert Tryptophan into Niacin, so need preformed Niacin (B3). Meat particularly chicken breast contains healthy amounts of niacin.
Try to feed the entire animal, not bits and pieces because nutritional profiles (including taurine) vary among body parts of the same animal, not just among animals/birds. Rotate among a variety of animals and birds, don't feed the same thing day in and day out because some meats e.g. chicken and turkey have lower potassium levels than venison and rabbit.
Cats need ample amounts of amino acids Taurine and Arginine, both of which are available in meat.
Use herbs and nutritional supplements sparingly as a significant number of the herbs and supplements good for humans are not safe for cats.
Loads of energy
Elimination of stomach problems such as diarrhea, vomiting, and constipation
Improved muscle tone
Smaller stools with virtually no odor
Clean sparkling white teeth
Nice clean breath
Elimination or decrease of itching and allergy problems
Maintenance of ideal urinary pH (6 - 6.5)
Strong immune system leading to better resistance to infections