Anyone notice a difference in the sound of your engine when you're in a drive thru or next to a wall? I use 87 and when I'm in a drive thru, it sounds a little more diesel-like. When I'm just at a light, I can only hear the exhaust.I'm sure the sound bouncing back from the wall allows me to notice the engine sounds. I'm wondering if this is what everyone calls a "knocking" sound. I get better gas mileage with 87 and same performance as 89.
My friend says if you have a CAI then the "firing of the pistons" is more noticeable and this could be what I'm hearing. I guess I'll fill up with 89 next time and see if I hear the same thing.

 

welcome to the world of the "hemi tick" don't worry we all have it. I have a superchips and fill her with premium and I still have it. There are about a million threads about it so with some simple searching you can read alot about it.