What ration should Prominence and Density be at for KW or KW phrases??
I'm trying to optimize a site and have my main KW at a 40% - 50% prominence but the Density is between 6% and 14%
Don't waste your time with these concepts. A keyword doesn't even have to appear in the content in order to rank highly for it in the SERPs.
Just build content naturally using effective use of the language. Study the roots and meanings of words and employ semantics. Learn how to write well essentially.
It is much better to outclass a keyphrase competitor with rich content rather than to overpower it. Overpowering techniques generally are not sustainable. In developing superb content, its significance is retained much longer while others grow stale rapidly. Your effective content will not require as much reinforcement or need to be refreshed as quickly as mediocre content will.
On another note, something to always keep in mind when developing content, strength in content comes from its own credibility and is more rewarded than anything else artificially enhanced.