I'm still "new" to the 5.0 crowd, but this thread is right up my alley...
I own a 2000 Kawi Ultra 150, and love every minute of riding it. A good friend who I ride with owns another Ultra 150 and also a Yamaha 1300 GPR, which I have ridden on several occassions. I can talk skis all day long...
Let me know what your plans are for riding. Such as what lakes (great lakes, small inland, ocean?), riding single or doubling up with g/f or wife, looking to go fast or jump high, fuel economy or all out performance, etc. Then, I can give you my 2 cents on what to get.
As mentioned earlier, pwc today is a good website.
www.ultra150.com is a good kawi website.
As for my ski, I have ADA o-ringed high comp heads, Solas intake, blueprinted pump with a 17/21 Solas impellor, TDR waterbox, Shredmaster rideplate, Worx sponsons, triple pis*er cooling lines, Hydroturf mats, and a custom seat.
If you don't want to post here, feel free to PM me. Oh yeah - please don't buy a Sea Doo.