I've taken my stock Showa apart and decided it was not worth to
rebuild... technically speaking the piston seal in the shock shock
employs the cheapest material possible... that material is like a gob
of RTV sealant and does not expand sufficiently enough over time and
during hard use... so as the shock body ages and then heats up the
clearances between the piston seal and body grows enough to allow
fluid blow by... the result is the back end of your once planted RC45
begins to moves around a bit...
After market shocks like Ohlins employ the best material possible namely
a Teflon expanding seal around the piston that has the
ability to grow consistently over time and during hard use...
My Ohlins Rear Shock was only $680...