The IIS thread search was easy, and the US distributor website is now
http://www.carbonscopetubes.com/Home_Page.html. Unfortunately they don't do an 8", but start at the 9.25 and upwards. Probably a bit of an overkill for a sparsely-used C8 anyway....
I'll just stick with Marc's mod for the moment. As I commented some threads ago, the C11 does seem to be the sweet spot in the Celestron range anyway. I'll keep an eye out for one on IIS.
