Sounds great! Internal hum is minimal or non-existent depending on RPM or exhaust performance. I have the downturn right in front of the rear axle and it's still as quiet as can be! It doesn't interfere with my music at all and I can have quiet conversations and really hear the other person. However, she can scream if you put her on the floor! I would recommend this instead of the louder 40 episodes all day. It's loud enough to be heard when you're walking down the street or when you want to be noticed.