i hear you guys all the time talking about changing impellers,etc how much performance gain do you get with this change,is it worth it.is it like a car when you change the gearing you might gain on one end but loose on the other? my machine is a 99 gsx.and how much are the impellers,are they expensive?and is it a big job to replace them? any help on this would be greatly appreciated! this is my first ski and want to learn as much about it as i can again thanks!