I have gotten eliminations at such extreme ranges the people literally didn't know what hit them. Also very, very quiet with most aftermarket barrels. Barrels are also easy to find because of the popularity of ICD's bushmaster. An expansion chamber also helps a lot, but is not necessary. And the great things is, its always ready for action.
Velocity is perfect right out of the box.
The stock barrel is decent. The dual bottle setup is really nifty. It shoots very fast. If I had to choose again I would still keep with the Alley Cat. This is, in my opinion, the best gun you can get for the price.