The Pipe is pretty loud. The Freak isn't too bad, depending on what front you put on it. Scepter is pretty quiet.
If you don't want to spend the money for a full multi-bore set, look at a low cost, large bore aluminum barrel like a Dye Excel or an aluminum CP or Powerlyte barrel. You'll be spending a lot more than you need to if you only get one insert/size for a multi-bore set. (Dye Excel ~ $40, Freak with one insert ~ $110)