Since nobody else will do it:
If you get a louder exhaust, you're going to need to change the EFI. That's usually done via reprogramming or adding a device such as a Power Commander from DynoJet.
There's probably a dozen choices in aftermarket exhaust from Cobra, White Bros, Vance and Hines, and others. As suggested, you can drill or even bang the baffles out of your existing mufflers, but if I were you, I'd save the stock exhaust for when you sell the bike one day.
Plan on spending about $800 or more for the complete setup with EFI update and pipes.