You are probably fine, but I believe they do better with a little more octane. I did have an 04 hemi truck and I always ran 87, but if I could go back in time I would probably have run atleast 89.

I only say that because of what I have noticed with my 2010 challenger. I run 93 now because of the tune, but I ran both 87 and 89 with the factory tune and data logging showed me quite a bit of knock on hard runs. I will also say that I could not hear it so just basing it off of sound doesn't mean it isn't happening or trying to happen.

just my .02