I remember a conversation about copying th 04+ GP GTP high octane table to the 97-03 bins a long time ago in the PowrTuner forum a while back. I copy or have copied already a lot of information from the 05 GTP to my 97 bin. This table was one of the first I noticed when comparing tables from stock binary files.
A big thing that some people leave out, are you copying the other spark advance tables as well? (if just cheating and copying the table over)... EGR Spark Advance tables are different in the later years as well and can add quite a bit of timing advance as well.
For me, down in those low cyl mass areas of the table, knock has never been a issue/concern running premium (91+ octane) gas. Walking a guy through tuning a bit, I have given him starting files or just plain modified files by myself that include tse basic copy/pasting of the high octane table.. Maybe it is a placebo effect, but he has commented about a change in lower throttle position response/power. Plus, does not see any knock in those cells either.
I have copied the EGR spark and every timing advance modifier I have found from one to the other. A safety note for those of you who might be concerned, there is a Max Spark Advance limit value (set to 50*) in our bins, that the PCM will not go beyond (unless you were to change it). I have had advance to 50* (not due to a single table, but combination of main and modifier tables to get a net result of 50*). That said, no KR even then, but it really didnt feel like it gained anything with that much either. Turns out, I am running a stock 05 GTP high octane table with only a few additions to the table in rather high cyl mass ranges and have been quite happy with it. (Been using the 05 advance, or more as described above, for more then 2 years and averaging about 400+ miles a week)
One big mod that will probably have an effect on how such a large timing change as this would effect an individuals car, have you disabled the EGR? If you look at the 04+ series III high octane table, you should see the EGR spark tables.. In certain RPM/cyl-mas combinations, it can add another 10+* of advance. For 97-03 (and I guess the odd 04 series II guys), the 04+ series III tables should be alright as far as safety... Do they gain anything (or worse, result in a loss)? Well, that is for you guys to find out with your unique mechanical/physical and other tuning mods.. I would dare not say it is a given MPG increase for everyone.. Just might be if you have everything else just right for the extra advance.