Running rich........

My cars AFR is between 15 -16 and pretty much stays that way. I was told that its dangerously high and it should come down more around the liking of 12 -13. Is it really dangerous? Do I have anything to gain as far as performance goes if I get the AFR to a reasonable level? Would a FPR correct my situation and if so how many PSI should I set it at? Thanks.

Well I had my car dynoed and they also did a AFR test. Thats how I know. I also know that it runs rich cause theres a strong smell of gas when I get on it. Others have said just from the smell that my car runs too rich.