Vinpocetine (for focus; but be sure not to exceed 10mg)
Rhodiola Rosea is useful, as it helps elevate phosphocreatine levels and boosts ATP synthesis, amongst others.
No need to add carnosine. Beta Alanine works by boosting cellular concentrations of carnosine. It is the more economical way of boosting carnosine levels, as straight carnosine on its own is rather expensive. Besides, carnosine is a dipeptide made up of beta alanine and l-histidine. So, when you take carnosine on its own, it has to be broken down into beta alanine and l-histidine, before the body can make use of it. To cut the story short, prefer beta alanine to carnosine for boosting carnosine levels.