One day, while stopped at a light, I heard a nearby car ideling. It obviously had a modified exhaust system but the really strange thing was that it sounded like you could hear each individual cylinder firing. The pulses were slower than I'd ever heard a car idle before, slower than 2 pulses per second!! I tried to keep up with the car to ask the girl driving it what kind of set up she had but we got separated by another light. I've always wondered about the unusually slow idle sound of this car. Has anyone ever heard this kind of thing before?

I haven't. Did it have a lopey idle?

I'm not sure what you mean by "lopey idle", but it sounded steady and strong.