What exactly does the resonator do?

[Ownbot]

When I bought my SVX it had a pinging noise coming from the resonator. I had my mechanic check it and he stated the there was a broken off weld inside in. Instead of paying big bucks for the part from Subaru, I just had him cut it out and replace it with a strait piece. There seems to be a small leak now and this junction. I wondering if eventually it will seal itself up as it starts to corrode, rust, and the carbon builds up. Its too loud for me now but even if/when I get the leak resolved would it still be louder because I no longer have the resonator?

Thanks