Perhaps a stupid question, but I have recently noticed that the stock exhaust on my 2013 Si sedan has grown a little louder. It has about 11,000 miles on it. Do stock exhausts "break-in"?
I bought my SI with 15,000 miles and the exhaust was pretty quite. I have about 21k on it now and I notice when I turn it on now it kinda growls a little more aggressive and sounds way louder even after it warms up, so I say, yes it maybe possible stock exhaust "breaks-in" lol