Is the M13 mouthpiece usable with any other clarinet besides an R13?
I'm trying to get better tone, and my parents are agreeing with a new mouthpiece, not a new clarinet.
I use a Selmer Goldentone now, crappy, but its worked for me.
How would is compare to the M13?
I can't go to test them out, as nowhere near me carries them.
Also, would the M13 be a good choice? The M13 Lyre? The M15.
Theres so many!

For what horn? I use an M13-Lyre, but I work in a band hall, so I can try it out on most any type of horn for you.

Its an old Artly.
Have you tested the M13 normal one?
Which one has a better sound up high?
I'm talking 2nd G above staff high, its a common note for me.
I like the closeness of the reed to the mouthpiece, so a 13 is the way for me, but I dont know which one.

No, I've only used the Lyre "Profile 88" version. It uses a harder reed, and is extremely reed-friendly. I find more reeds in each box that play reasonably well without modification than with other mouthpieces I've used. The upper register is superb, easy to play.

What brand and size do you use?
I really like Vandoren 3.5, I just switched to those from Mitchell Lurie 4.
Crappy reeds when it comes to tone.