Hi and welcome to the SeaDoo forum.
That's kind of an old ski, so parts are not readily available. We have a guy on the forum Nick [MENTION=41828]Minnetonka4me[/MENTION] he's our go-to guy for parts that may be able to help you out. As far as a performance impeller try the Solas website, but unless you need a new impeller anyway, you really won't get much bang for the buck.
If Nick doesn't respond on this thread try PM'ing him.
Lou