They are 671 tib's. I was told at survey they are 485 hp but I would think they are actually 450's. I haven't checked the injector size to verify though. They show no scoring in the cylinder walls or rings. The heads have probably been reworked. Turbos and etc have less than 400 hours on them. I keep getting the oil analyzed and all is coming back okay. So far so good. I have run into a couple of people who have over 5000 hours on their 671's with no majors yet, so they do hold up if you service them well.