Go here to learn more about Mousse Can Mufflers:
http://www.swanyshouse.com/moussecan/mcm.html
These MCM/MCP setups can produce the substantial power boost of a real tuned pipe at a fraction of the cost.
Unlike a real tuned pipe, MCMs/MCPs don't require critical tuning of the header length. And unlike real tuned pipes, MCMs/MCPs produce the power boost over a much wider RPM range, resulting in a much smoother throttle response. The smoother throttle response is why MCMs/MCPs are preferred over tuned pipes for 3D flying. And the sustantially lower cost is why MCMs/MCPs are preferred over tuned pipes for everything else, except for all out speed competition.