how many muffler mod videos you see milling? Most mod to increase performance via rpms, imagine that.
Have to throw in a comment or two. I disagree with the premise that most mods to increase performance are about increasing RPM's. For me many saws also have limited ignition coils. The Husqvarna 372 X-Torqs, 576xp; etc. are examples that come to mind. Certainly you can change the port timing, increase x-sectional area of the transfers etc. along with going with an unlimted coil to jack power and RPM's. Now you have spent 1/2 the price of a new saw in grind time (Time is money) and a decent ignition (Not $15 dollar AM junk)! But that isn't the only way to boost performance. Compression alone can make a huge difference. That's why for a long time simple base gasket deletes for many of us and then pop-up piston builds have been a staple of performance hops. Compression increases work well to boost power at "standard" RPM's by increased efficiency of the actual combustion, and along with the right "squish"; actually increases the amount of charge burned vs. a standard squish distance typical of a stock saw. Its about performance increase vs. dollars & time spent. Of course that's effected by what tools and skills you have vs. have to hire out! I do my own work. I might not win any cookie cutting contests but I have fun, cut a **** load of wood....and really enjoy a sharp chain on one of my own builds when out in the woods making chips...
As someone mentioned before power isn't the only motivation for muffler mods...and as you mentioned before the muffler and cylinder temps do raise in cuts only to rapidly drop...on THAT saw. Some of the new designs have, for reasons only known to the designers; (suspect epa/efficiency) trapped the heat and radiate that heat through the bottoms of their mufflers back to the cases. On a hot day with longer than 20inch or 10second cuts this does increase the saw's overall temperature. Some even have heat soak related re starting issues when other factors are added to an already heat stressed situation. Smart muffler mods can help heat escape with obvious benefits. And yes I have measured cylinder temperatures.
For the typical hobby wood cutter type cheap performance increases done by them on their own saw can be worth more than the most sophisticated built saw done by someone else. Things like muffler mods along with increases in compression with no base gasket builds ( On some saws) returns the instant gratification of seeing a difference that is priceless for the tinkering crowd who prides having ownership and interaction with their mechanical hobby of choice. Same metric with Cars, Motorcycles, even firearms. And as always every saw is an individual so some will see greater changes than others....but the bottom line is on the saws where its possible a compression gain along with a muffler mod makes a noticeable difference at minimal cost. And its your mod.
Oh yea....its REALLY easy to get caught up into the online measuring stick mentality and really over analyze this crap! Stock saws have cut a LOT of wood for a very long time!