Bonneville America Forums Forums Technical Forums Exhaust Specialty Spares ESPECIALLY loud!

What you described is what we (in the industry) call a plug and plate - the main flow pipe is plugged forcing the gas out through the perf into the outer case - around the plug - and back into the perf. This is very restrictive. And I suspect this will be louder than your current glass packed straight-through system.

For "plug & plate" to work effectively (silencing), this in/out process would be typically repeated 2 or 3 times along the length of the muffler - but in your case that would necessitate plates to create sub-chambers. Hence "plug & plate". But inserting plates into you existing muffler is difficult.

I think the simple plug system you described may be too restrictive for our bikes - but I could be wrong. As well as being louder, it give you a different note from your current straight-through muffler (straight perf with packing) - possibly more higher notes because of the lack of packing (fibreglass absorbs the higher frequencies).

For clarity this is what we call a chambered muffler:
A chamber muffler has an expansion chamber where the gas flow into the chamber is not obstructed or restricted - it expands and then exits out through another perf (packed) tube. This would be hard to build as a modification because of the same issue with the plates mentioned above.