"ST61 PDP Bluehead with old flow thru muffler, jeez is it loud!"

I have that exact muffler on one of my Blueheads. I don't know why they call it a muffler, because it doesn't. I took mine apart and screwed a large sheet metal screw into the flow through venturi from the inside. That quietened things down a lot but unfortunatly also robbed quite a bit of power.

The good news is tha most any 60 sized ST muffler will fit this engine.