I think I made my original post too long, so more pointed specifics here. I am interested in a Bad Boy, probably 60", to mow 5-10 acres and run me around 12 + acres. My drive way has steep hills but the areas I mow are flat. Since I operate a dog park on my property I would like to have something that is quiet so it does not disturb people and dogs who are there most of the time. I drove a BB 6000 LightningZ with 26hp KawasakiLC (liquid cooled) engine and it seemed quieter than the Kohler engine. The dealer did not have any of the diesels in stock so I did not get to hear one. Is this one of the quieter BB engines? Would I be correct in assuming the LC engine will run cooler and probably out last an air cooled engine in the hot north Atlanta environment? How do the diesel engines compare to the gas engines in terms of noise? Thanks for any & all information.