Well, got my newly threaded large letter Bach 7C back from The Brass Bow today and got the opportunity to try some backbores with it. I'll be updating y'all on the real results as they come in, but very briefly here's what I've found so far: The total thing with a new backbore cost $75 without tax. I started with a 5 backbore and found that somewhat resistant, but to be put aside for further persuit. Then, I tried a 6 backbore and actually found that too open for my purposes (so much for the 7-9 range comparing to a Bach 10 :wink: ). Then, I went back to the five and decided that was a closer match to what I was looking for due to the fact that my primary playing is big band and college pep band, both high-power groups. Also, this definately had noticeable resistance and brightness over the Bach #10 backbore. Anyways, I ended up settling on the 5 backbore and brought the whole thing home to give it another whirl. I ended up being able to play above high C without turning 40 shades of purple (just three now ), and I actually squeaked a Double C up there on accident when I was aiming for a high G. So far, I'm thinking this setup could work for what I'm doing, but the real test will be tomorrow, Saturday, as I play a double header in the pep band which equates to quite a bit of fff and high playing. I'll keep you guys posted, but I think having the 7C threaded will work to my advantage in the long run.