I'm going to do a measuring run on JBL M2, 4367 and VTX waveguides the next few days.
I will try a few different dia's in 2450SL, and 2451 cores. I'don't have an Mg dia and not sure it will take apart my other system to get to the Be's.
I will prost some findings here and if someone want the raw data just give me a shout.
Kind regards
//Rob