A muffler is a silencer made with different chambers, and gases slow down in them, while a resonator is a straight drilled pipe with some glass absorbent around it. I previously had a NA 2000 cc with 180 HP, and I swapped 63 mm exhusts with 60 mm, and I noticed the difference (dyno too). Perhaps I'm sensitive. Supersprint factory is 30 km from my house, they don't use mufflers.
Muffler and resonators:
https://www.cjponyparts.com/resource...-vs-resonators