What hoses are you fitting at the back (to drums)? The best scheme for a standard rear disc is a single 440mm hose (post 2002). It will work on a ST170 disc as well, though a bit tight on full travel. There are various hose/pipe/hose setups on earlier rear discs and also on the ST170/RS and having the right brackets and hoses can be great fun.
Cheers, i will defo bear this in mind, thanks for the heads up ;0)