Hi,
There may be some different exhaust you could buy which would be louder, while still being just as restrictive as the stock exhaust.
The issue with rejetting is that a louder exhaust is generally also going to be less restrictive, meaning higher throughput. In a fuel injected vehicle, the computer adjusts the fuel injectors accordingly. But a carborator needs to be rejetted to make the same compensation.
Check out this video about the topic:
Following mrmaxstorey's guide rejetting isn't too difficult if you were just afraid of the work.
I would think that if you were to drill holes in the baffles you would get a bit more flow. You could always try it and then check the spark plugs to see if it is running lean. If it were running fairly lean you would need to rejet.
