The best replacement for muffler is resonator.

The best alternatives to muffler are rated as following:
★★★★★  resonator
★★★★★  scarf
★★★★  no muffler
★★★  exhaust
★★★  catalytic converter
★★★  glasspack
★★★  straight pipe
★★  cat back
★★  exhaust system
★★  catback
★  exhaust difference
★  silencer
★  full exhaust system
★  resonator diesel
★  straight pipe cummins
★  cat back exhaust
★  quiet walk
  straight pipe diesel
  performance muffler
  full exhaust
  flowmaster
  straight through
  cold air intake
  scarf difference
  baffle
  straight pipe duramax
  chambered muffler
  axle back
  hotdog

Your alternative for muffler is not listed? Suggest!
Speaking about muffler, one probably shouldn't forget about resonator.

Other search terms related to muffler and their ratings are:
★★★★★ resonator
★★★★ dual exhaust
★★★★ turbo
You have in mind a companion for muffler and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of muffler in all years. Click on graph for more.
muffler
resonator
scarf