They did not release the older more performant model to the API. Please ask them to on the Discord or Twitter. But I think they will not. There is too much demand to handle and the older "less streamlined" models are very problematic for them (based on the fairly constant API/ChatGPT problems and well known incredible demand).
I get the impression that until there is a significant amount of excess capacity, they will not put out new larger/slower models, so the only way you get a better one is if they can still make the next ChatGPT model release just as fast/"lightweight".
My suggestion is to find specific abilities that seem to be lacking in Turbo, and try to get a message to OpenAI staff about it with a request to attempt to improve the next ChatGPT model in that way.
Having said all of that, text-davinci-003 is still available.
I get the impression that until there is a significant amount of excess capacity, they will not put out new larger/slower models, so the only way you get a better one is if they can still make the next ChatGPT model release just as fast/"lightweight".
My suggestion is to find specific abilities that seem to be lacking in Turbo, and try to get a message to OpenAI staff about it with a request to attempt to improve the next ChatGPT model in that way.
Having said all of that, text-davinci-003 is still available.