Freeze plugs or expansion plugs are in engine blocks.  I believe they may actually be used to plug the holes used to remove the cores from castings - but they are commonly called freeze plugs - and I assume they pop out if the coolant freezes and saves the block from being cracked by the expanding ice.....not sure.

Anyhow - for this muffler a freeze plug could be installed in the center of the tube to force the exhaust to pass through the perforated holes on the inlet end.....then back through the holes on the outlet side once the exhaust passes the freeze plug.  This reduces noise by buffering the exhaust pulses.

Demin wrote on 06/08/14 at 06:49:01:


Huh. I love my Frisco's. I hate pullback with a passion, and want to destroy the buckhorns that came stock on the bike in some pagan ritual to the motorcycle gods.  I do wish they had a bit of downsweep, but pullback? Hell no.

For me, rabbit ears and chopstix look like the most uncomfortable bars I can imagine, and I've done 4 and 5 hour rides to visit family in Tobermory with my Frisco's. Only stopping for gas, and had no problems at all.

Different strokes....