You got any photos of the setup.
A picture is worth 1k words.
I must admit that I have never posted a pic here at Stunt Hanger as I really don't know how to mate!
But please accept that the new Merco mufflers are exactly the same as the old in design and the bolt holes perfectly match the LA 46.
I have seen the run characteristics of a standard LA 46 with muffler and then with the Merco muffler and the run seems to be 'enhanced' or more consistent in some way.
The thimble insert idea harkens back to the old SuperTigre 46 days where it is shed loads easier to loosen the two bolts holding the muffler together and swap out to a different thimble rather than change the venturi insert.
But if you really insist I can get pics of my mates LA 46's with Merco mufflers and learn to post I suppose (or Rustler can chime in here and post pics of his products for me! Ian, where are you?)