You can edit the Decay Rate for an individual sample on the MISC page of the
sample editor. So you could edit that sample and save it with different Decay
amounts as several different samples.
When you save to a different number, the Kurzweil will ask if you want to save
the sample data as well. If you answer yes, it will make a copy of the sample
data, thereby using up more sample RAM.
If you answer No, then it will save only a sample header, consisting of the
Start, Alt, Loop, and End points, plus the values of the parameters on the MISC
page. This obviously saves sample RAM., But the disadvantage of this method is
that if you make any changes to the original sample that actually changes the
sample data itself (by using any of the DSP functions) it will affect all the
sample headers that access that same data.