It all depends on what type of car/setup the system is in. My friend has 2 audiobahns in a car, and you can hear him a little ways away. I have a system that is louder than his, but its in a 1500 chevy extended cab, and you can't hear it quite as good. I'd say anything around 130 DB's is starting to get loud.
i've heard that systems are louder in older cars for some reason like the late 80's cars and early 90's cars does it have something to do with the metal that they make it from or sumthing? i dont know
Lol... you should be able to hear that! I have also noticed that they are louder in old cars... could be the mettle... and old cars aren't as safe, so I'm guessing newer cars have different material on the inside... kind of sound proofing them.