In my personal opinion 100% Xscream 900rr. If you are looking for a competition motor that will do pretty much everything possible on a Jetski that is the motor you want. I have ridden many different 900's and nothing compares to the never ending power these motors put out. But when considering what type of motor you are looking for, you need to think about what kind/style of riding you want to do. The first thing you need to consider is that these two motors are setup to do different things.
From personal experience, I'd say that the DASA 900 is going to have a little more low end snap for the first trick but will most likely run out of power and kind of flatten out pulling wise once you go into a multiple trick combo.
Now looking at the 900rr, this motor is primarily setup for multiple trick combos and never ending power! It is going to have way less snap down low depending on your carb setup. My personal ski is very "muddy" down low but once you get into the throttle it takes off like a freight train and never stops pulling! It is a little challenging to get use to the power band but once you do(only takes a tank or so), there is an endless amount of power coming out of the motor.
Not trying to sell you on your decision, just wanted to share my personal opinion on the topic..
And Yes, it just so happens I have a xs900rr sitting on my shelf that I have up for sale. It isn't brand new but it is pretty damn close. It has had about 40 gals of race gas through it which is roughly 7-9 hours on the motor.
I hope all this helps with your decision. Please let me know if you have any questions regarding how the xs900rr ride or really anything about them. I am pretty familiar with them and am more than willing to help you out!
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