Just to check, you want an expansion chamber to be around the same volume as the cylinder/head/intake right? If you have an expansion chamber larger than said volume does it lesson the effectiveness of the chamber? Or is this not a concern? I only ask because I stumbled upon an old thread... In the thread the OP shows an exhaust that he modifies to fix the standard 66cc/48cc bike motors. Super simple to do too, But the exhaust has a pretty large chamber. The Arrow Snake Pipe is also pretty big but I'm not sure if the two pipes are comparable. Whats your thoughts on this guys?