G'day Playford,
I just took the outer muffler cover off the saw. Drilled at an angle with a step drill (although large normal drill will do). INSERTED pipe thru just a tad, but only welded on outside on a very LOW setting with a mig. Sprayed with high temp paint and haven't touched it for years.
Always take off muffler so no shavings end up in your cylinder. Its a good chance to clean all the carbon out too. I think I actually left the spark arrestor in this one as I use it to cut firewood (which is often in dead grass).
To be honest, I never really noticed any fuel reduction, mainly power and faster cooling.
Cheers
