Thats absolutely absurd!
It doesn't matter if you have a restrictor or not, the epa guy should take it at face value if your exhaust is quiet or not. Otherwise that would be like saying "oh im sure you have a louder exhaust at home, so im not gonna check it till you put that one on".
It should be irrelevant how the exhaust is made quiet as long as it passes the noise test.
my 2c.