THere is virtually no difference between the 2004 6****** and the 2005 version. The side-cut and materials are the same. THe only difference is the binding configuration. THe 2004 piston set-up is such that the piston was placed between the heel and toe of the boot. In 2005, the piston was moved forward so that it lays just in front of the heel. THis year, there is also an extension of the integrated system in that there is a metal bar that is connected to the piston that screws into the ski about 1/2 way between the toe and the tip. This makes the 2005 slightly more damp than the 2004 version. I own both skis,,,,,,,,,. The 2005 6****** skis a bit more like the 2004 5*****. Both skis are awesome carvers on hardpack thru 3-5" pow.