After a decent outing and finishing on a nice stretch of road where I can wind it out through 2nd gear before turning into my neighborhood, my car is putting out a very loud "pop" about every 15-20 seconds coming from the exhaust system (after the engine is turned off.) This lasts for about 3-5 minutes but is pretty annoying. My dealer says this is normal for the 2000's but I'm hoping it has something to do with it being a new car (about 300 miles) and wll go away after some amount of break-in. Any thoughts?

 

It's normal. It's just the exhaust cooling down. My car has 31,000 miles and still does it.

 

First car you've owned?

Not only is it normal for the S2000, it's normal for every car I've ever seen/heard. It's simply a result of the metals in the engine and exhaust system cooling down.