1998 is the only year Perf Shift will light up in the Cluster as far as I know, otherwise it will light up in the DIC. You can add the Perf Shift in the cluster too as long as you have the right socket + blub.
I added it to mine so when Perf shift is on my DIC lights up and so does the cluster. I added it because I had a spare blub and socket laying around. Figured what the hell, right? :-)
NOTE: I don't know if this will work on 2001+ that don't have Perf. Shift factory wired up.