I know that this is a very old post, but one point I would make is that as far as I know (as an owner of a 2008/9 Contessa) C9 Cats were 400 HP until just prior to Monaco shutting down in 2009. Only thru that late production period did the Cat supposedly have 425 hp, achieved by computer tuning I was told. Mine was sold as a 400 hp, does not require DEF.
Our coach has 40K and never had an engine/turbo issue. I have always followed the warm up and cool down suggestions posted on this thread, and hope that keeps my engine, and me, happy!
Any comments by experts would be appreciated.
