I think, quite honestly, this may be a matter of one's definition of "Projection".
Modern horns are brighter and reedier (yes a generalization, but with foundation). The Tonal Paradigm (a term I borrow from Tim Price) of the sax shifted with the introduction of the Japanese brands to the market in the 70's-80's. A brighter sound came into favor in that period, which makes sense if one considers the genres of music a sax was most involved with in those eras.
So the change in tone resulted in sax models being able to sonically 'cut through' the band contexts 'better', in a sense. More focus, more brightness. The flip side: the lushness, width, and darkness has been sacrificed.
So, yeah, I would tend to agree with someone if they said 'my Yama cuts thru more than my Conn'. I guess if that is a main sonic factor to you, then perhaps a modern horn is more apropos (although to me it always still begged the question: perhaps turn up your levels in the sound mix ?).
As others have replied, I would not consider a 6M a 'tame' or 'quiet' horn in any way, shape, or form. Everything about it, tonally, is 'balls out'. But if you want it to 'cut' like your Yama...a Meyer is a poor mouthpiece choice. I would experiment with mouthpiece selection if you want to get more 'edge' out of your 6M.
Have a tech heck your current pads, to make sure there are no significant leaks. Make the horn leak-free. Then investigate/try some other mouthpieces; checking both for tonal signature AND intonation up and down the horn.
I'd probably do THIS before repadding the horn with a certain resonator style, as I think a mouthpiece switch would be a more cost-effective move which would result in a more dramatic sonic change.
Best of luck.