In addition, they choke down the exhaust to comply with emissions ... at the expense of performance and saw life! Excess heat kills saws.IMO that's partly why virtually all modern saws benefit from muffler mods. Less heat equals a better work saw, it's just a fine balance between power/heat dispersion and excess noise.
The standard is just plain "stupid"! It is based on particle/hour based ONLY on the size of the saw. Which means, you may have to give up 20% performance to PU 5% better emissions and that is OK!!! It is just plain stupid!