well, I'm about to find out. I too just bought one. From what I hear (I hope they are right) that after 2008 they did some improvements, my new ride is a 12 which, besides being the next to last year for that engine, they did improve ratings (IF they can be believed) to 9.8:1 CR, 310 HP. If true (and even if it falls short by 60 hp or so) that is most HP in any vehicle I have had. I have seen/heard multiple places, that the newer ones with 16 spark plugs (which is what I got) are supposed to be much better about issues like valve seats not dropping as readily and not so sludge prone as the earlier ones. I got a former Fastenal truck (but there was 2 owners in between