I bought my new Z with the 60" deck and 25 hp Kaw engine this spring. It was the most engine my local "new dealership" had in-stock. I say this because I did initially wanted more engine but he would not give me the same deal on ordering a machine as he would on buying current stock. I was willing to pay the "list" difference for the larger engine, but he quoted $1k more and assured me that the 25 kawasaki would do fine. Unfortunately, he never saw the terrain I use it on. I think he was just moving his stock mowers before ordering more. Before getting to the issue I am having, I need to say that my Z ranks far above any mower I have tried or owned in its quality, construction, and design. I am amazed at the perfect cut it provides, even at higher ground speeds. Its fuel efficiency, control, ease of maintenance, and just overall layout overwhelmingly prove that it's truly a great mower. I wash it, check it over completely, and maintain it by-the-book before and after each use. The limitation it seems to have is only experienced on one steep grade I must climb while mowing each week. But this problem is a potential threat to my safety as well as possibly stressing pumps, etc on the machine. It is a problem I would like to resolve - if possible. I climb this hill only straight-on, because it is very steep. When I reach about 10 ft. from its crest, the engine is nearly choked out - even though I pull back my ground speed as much as possible to try to relieve it. I don't dare come to full stop for fear of stalling and sliding backward. I can tell by the way the machine shutters that it is straining hard to stay alive. Even though this period is brief, it is less than comfortable - and I like the Z too much to think I might be abusing it. I don't know what options I have. It only has about 25 hrs on it and I can't really afford to consider upgrading it and taking a loss. I considered buying the Super Z at first but it exceeds my budget. Any suggestions for remedy?