Finally Superfly might be right about something.
Yamaha is the ONLY way to go.
However - NO MATTER what type of engine runs your sled, (assuming you have a pump on it) you NEED to check those bolts every now and then. Ideally when it is new (FACTORIES DO NOT DO THIS) back them out and use never-cease on them. Dont use lock tite, as you may actually WANT to take those bolts out to service the wear ring and or impeller. Never-Cease will stop the vibration from backing them out.
Also in Wrangell, AK where the boys do alot of backcountry jet boatin' - they take a peice of 1/4" nylon rope and tie that boot to the lower unit. THat way you CANT lose it. If you have to do a streamnside repair, or the bolts do back out, thats your safety line.
Hope this helps.