modified cobra mic

I have a friend who took his cobra 29 in to get peaked and tuned and while he was their they where telling him about getting a noise cancelling mic but he told them he didnt have the money so the tech took his stock mic and put foam inside it which i understand for noise then he said they soldered a flat round capasitor inside( a milar type I assume ) but im not sure what value it is and where it was soldered to and thats why im wondering if anyone here has heard of this cause when he got on the air people told him it sounded like he had a high dollar mic when he didnt have one just some mods to a stock, I would look at his and find out but we are both on the road and dont cross paths often and he isnt into it enough to be able to tell me correctly what was done.