What octain fdo I need in my 03 stratus coupe r/t 3.0 v6?

My choices I think are 85,87,89 and 92/93.

Which does this car need?

If it only needs, say 89, what will putting 93 in it do? Speed it up? Engine longevity?

Thanks guys!

 

If you read the manual, it says 91 octane is recomended for maximum performance.