Go to corner of San Vicente and La Brea ave., (before Pico Blvd) very good mufler shop they will do it for you and will take pic's for their records and display for other cusomers. Few years ago I've done my mufler there for MBZ ML320. Job was done in 10min, they are professionals.
They still there, I drive by this location every day to work and back.

P.S. If you will go South on La Brea Ave., shop will be on the west side (right hand side)of La Brea Ave., (before Pico Blvd)
if you will be going North on La Brea- shop will be on the left hand side (passed Pico Blvd).
Good luck.