dream demo had a pre production model that was juiced up a little bit to get the 69.2 mph stock speed that they claimed, also like you said there was low humidity and a very cool day. kawi prolly tuned it down a little bit for the public to make it more reliable.

interesting about the kawi 250 when i 1st bought my ski on july 3rd 2007 i looked very hard at the sea-doo gtx limited and the kawi 250 ultra ( the sea-doo was about 3 grand more in price ) as luck would have it the kawi 250 was sold out ( lucky for me )after working the numbers the salesmen reduced the price of the gtx limited to match the kawi ( he took 3 grand off )the gtx comes with a depth finder a gps and interloop cooling good for me since i'm on the coast of virginia with salt water but what really suprised me was the speed with my fat ass on it (235 lbs )and a girl on the back i still hit 65 mph ( readings from the gps not the speedo meter) and down the river there is a guy with a kawi 250 he is about 70 lbs lighter then me and with 2 on my ski and he by himself he can't beat me ---- needless to say he isn't happy about that -- this winter i will be adding a stage one kit on my ski and loose some weight and look for him next year unless he trades in his kawi for a sea-doo during that time --- i guess my luck was with me when i bought my ski i was planning on buying the kawi but with them being sold out it "forced" me to buy the sea-doo wow i was lucky for that !

if your down 1000 rpm you probably have a bad plug put the platinum NGK replacement get the # off sparkplug.com

Maybe to much oil in the engine.
These engines have to be level and set at the correct levels.