Laurel,
While we all have a right to our opinions, keep in mind that 100+Forum members run 2008 and later model year coaches, mostly with 2007 and newer CAT engines. If there were systemic issues with these engines, I think we would be seeing this on the Forum, but we are not. Don't get me wrong, I specifically verified my 07 had a 400 Hp C9 built in 06 as I wanted to avoid the problematic turbo issue in the C9S (425 Hp). My understanding is that the problem was, in the main, caused by a poor design by the turbo manufacturer, and that CAT has since employed an improved turbo that addressed the issue.
Steve