If you're getting leakage you might not have the header far enough into the muffler.

Ernie, would you be interesed in me running my .90 with the Swing muffler and the Mac's one piece

I ran my K .90 using the SuperTigre Swing Quiet muffler and the Macs Black one piece. My wife complained that the Macs was much louder even at the lower rpm.


Fuel Fox 5% nitro with 20% castor.
Prop APC 14x6 RPM with the Swing muffler==10,877
RPM with the Macs one piece========9,900
Plug==GloDevil====2 stroke standard.

Well here is the stock ST muffler after I painted it. It looks much better now than it did before. Kinda looks like the MACS muffler but just bigger... I will be cutting the cowling to fit now.

Didn't realize that this topic would generate such a wide range of comments when I made the initial post. The ST "economy" muffler mentioned in a early post looks very interesting and I will replace mine with one when I lose another expansion chamber. Although not all posters agreed with my dislike of the ST muffler, most seemed to agree. ST can improve their product in my opinion by going to a more typical "OS" type muffler. Thanks for the large number of helpful responses.

Mike H.

I would agree, Mike, but only if they sell it for under 20 bucks.

It is not worth more and it shouldn't sell as such.