On my 750 i put black rtv silicon in the impeller and when i pressed the driveshaft into it it oozed the rtv up through the splines, i let it dry before i ran it, then, i ran it all summer and when it was on the hose all you could hear was the exhaust, it completely eliminated the pump rattle, these kawi pumps dont spline very tight. I did the same on my sxr and i still have the rattle so i guess i didnt put enough in when i did it, im gunna try separating it and adding some more, if i reach my hand in the tunnel and grab the impeller it has alittle play on the shaft which my 750 didnt so im thinking maby the rtv settled weird and is causing the impeller to be off balance, which in turn would possibly be causing this vibration. And just a tip to anyone who does this, dont put alot of rtv because when you mate the shaft to the impeller , it is very hard to insert to push the thick rtv through the splines