Been using my Bach 6.5 AL and it is not bad, but I heard about the non Bach horns requiring a "thin walled" shank for a better fit/air flow. Any truth to this? Was wondering about the Schilke's but would like to hear some other suggestions. As for the year of my horn, probably made in the 70's, which unfortunately is one of the newer ones (the really good ones were the older ones). Appreciate it.