Think I've finally solved the problems with my GTI. Took the ski to the shop where I bought my XP and had them align the engine. It was way off....needed to raise the rear engine mounts 1/4" and the fronts about 1/8 inch to get the tool to slide in correctly. The dealer didn't have any thick shims, so I took the ski home and bought some fender washers from Lowes. Taped four washers together for the rear and 2 for the front. Found the ski has a rebuilt SBT engine, and I'm thinking the previous owner or shop didn't align it when installed. I'm also thinking the miss-alignment was probably the cause of my original cavitation issue as the carbon seal couldn't seat correctly.
Also found the impeller in the pump I had rebuilt was getting bound up on the wear ring and making it hard to spin. The dealer thinks the pump housing is warped, and I'm thinking they may be right. They said the ones with the brass fins (like mine) tend to warp more that all plastic ones. Since I'm not ready to spend the bucks for a new housing right now, I decided to try and grind the new wear ring where it was contacting the impleller. Used a dremel tool and sandpaper where it was too tight. Once I got it close, I hooked up my electic impact wrench using the impleller remover tool and spun the shaft for about 5 minutes. That really seemed to help and now it spins freely by hand. There are some spots on the wear ring (where I didn't grind) that are over specs, but I'm hoping it will still make decent power.
Got it back together and it started up. It was a frustrating week but was happy to get it started again last night! Saturday will be the true test on the water.
Would be interested to know if anyone else has used fender washers for shims or tried to grind a new wear ring that didn't fit correctly?