If you Google (debaffle Vulcan 900) you will find lots of links on how to do this. Even some videos on Youtube.
Basically, there are 3 stages.
1 - knock or drill out little screen in the center pipe (really easy - 30mins)
2 - cut away the black caps around the center pipe, cut off the end of the center pipe, drill 4-8 1/2" diameter holes in the rear baffle plate that surrounds the center pipe (a little harder and requires some special tools such as drills and metal cutting electric saw - 1hour)
3 - entirely cut out the rear baffle plate with a metal cutting hole saw (about the same difficulty as stage 2)
Some people will go to another level and knock out the catalyst screen at the front of the exhaust as well. And I have also heard of people grinding off the weld at the front of the muffler section to get inside and remove everything. Then they re-weld it in place.
As for sound...
1 - A little louder, but not much. Mainly you can hear some of the popping the engine does naturally that is masked by the stock setup.
2 - Moderately louder. You will notice a good difference when the engine is pulling hard. But it is still quiet enough to hold a conversation with your buddy at the stoplight.
3/4 - I haven't gone this far yet, but people say it is a lot louder. Some people also say it is a raw, untuned sound compared to an aftermarket exhaust. But that is a matter of opinion.
'07 VN900 Classic
Horsepower is an illusion.
Torque is the source of all good things.