Yeah, i opened mine up and pulled the guts out of it (except the packing) and threw a larger tip on it. Along with a K&N and jet kit it performs really well. It's loud as hell and not very pretty but i've certainly gained.
Just be aware that ripping the guts out make the exhaust illegal to ride on most public lands. That's a $239 ticket here in Oregon. Money better spent on a proper exhaust...