2002 GTX DI limited RPM

[SIDEWINDER]

I have 02 GTX DI that tops out at 6000 RPM. I have changed plugs & cleaned Raves with no improvement. Any suggestions before I take it to shop? It has good accelleration, although it hesitates a little before accellerating at WOT. What should maximum RPM on this ski be? Will running Seafoam thru it help or hurt? Is there any advantage to using higher than 87 octane gas? Thanks

 

[seadooya]

considering that yuor rpms are stuck at 6k, at WOT, i'd put my money on, that the water regulator (located on muffler) is bad.