Muffler mod etiquette.

[Marley5]

I'm an older guy, loner, quiet, non confrontational.
BUT I've watched and listened to so many videos and threads regarding muffler mods and most are half as*ed. Imo

Coming from the muscle car era of the 70's we put all our money in our cars to make them run faster for the big weekend drag racing.
Headers were a must to open up the exhaust but a common mistake was big pipes with no back pressure.
The car sounded great but couldn't even break traction.
Chainsaws:
Why are there so many YT videos of those gutting mufflers and opening up the exit bigger than the import, piston side.
In my mind this actually creates performance loss compared to stock form.
Yes, I guess I've watched to many videos this evening with excessive drilling and high reving Dremels.
Educate me

 

[Chevboy0167]

Main advantage...... heat removal. Keeps cylinder temps down. Engine as a whole runs cooler. Extends life of saw as a whole.

I believe rule of thumb is open up muffler outlet up to 70% of cylinder exhaust port size.

 

[jblnut]

There is something to be said about keeping a similar internal volume to the muffler can as well. I put a Bark Box on my 066 and thought it ran better, which I think it actually did. I recently put the stock cover back on and opened up the stock hole to around that 70% of the exhaust opening and I’m 100% sure it is running better and pulling harder.

 

[osadayo99]

We run WCS bark boxes on all our Stihl 362, 461/2 and 500i saws. Don't know so much about "more power" but they definitely run cooler and throttle response is much improved . Our crew works Wildfire and fire mitigation thinning in surrounding mountains ...during the summer months we're on those saws for long days, just the fact that they run cooler is worth the mod. Quicker throttle response eases the limbing and slashing process. Just my / our observation do'n the work on the ground.

 

[Patrick62]

I have modified a few mufflers over the years. Nothing ridiculously crazy tho.
You have to think about the whole system as it is a resonant (for lack of a better term) setup.
Look at the enduro motorcycles, and that giant expansion chamber. The plan is that the exhaust will cool, and create some vacuum to pull the next puff of exhaust from the cylinder. However... if there is too much, then it pulls more unburned charge.
At a certain rpm, the thing will work like a charm. The black magic is to make the thing really hot where you are at when cutting.
This opens up the next "rabbit hole" to fall into.
Porting... I have run two saws that were ported, and the results are there. This is where the mechanic figures by experience, and a bunch of scribbles on a paper, what to make each port based upon, carb size, exhaust size, CC of cylinder, etc.

Correct assessment, louder isn't always more power.

I do like that 70% measurement, and seems to be a good number to shoot for. removing the spark screen, it's your call.
Could get in trouble with some authority figures. I have a couple saws that are compromised this way....