it's a small sample size but both people I know with Guzzis had issues and constantly got stranded. One sold and bought a new Bonnie, the other sold and got an FZ-07.
My bonnie came with these 1" lower rear shocks already installed: https://www.newbonneville.com/html/ikon_shocks.html
My front ones are these: http://www.revzilla.com/motorcycle/progressive-fork-lowering-kit-for-triumph-bonneville
I got my local shop to do the front lowering for me as I didn't really have...