I would expect your 91 tune to be pretty close to the optimal timing. Setting the timing is more of a trial and error process, that should probably be done on the dyno, but could also be done at the track if you are VERY consistent (which you won't be!).
If you wanted to play with the timing at the track, you could try to make some consistent passes. Then, bump the timing 1-1.5*. If you can gain 1mph in the 1/4 trap speed, then it is probably a positive gain and you can keep it, and go a little higher. If you gain less than .5 mph per degree of timing, then it probably isn't worth the risk of detonation, because the timing is pretty well optimized. Of course, listen for detonation, especially at the top end and get out of the gas and back off the timing if you hear any. You could also find your car likes less timing than what the 91 tune has, so don't be surprised or confused if you gain mph by running less timing.
The tires will be another trial and error point. Do not change the tires and timing at the same time, or you'll just be confused. Change only one variable at a time and keep records. You can make notes on the time slips even, saying what the DA, tire pressure, and timing was.
Do you have the 555R or just the 555? If you have the R, then start with stock pressure and work your way down until you they hook well. I've found that there isn't much reason to go below 18psi.
Yes, removing the sway bar can help your 60'. However, it may not help much if you don't have the 555R. If you have the regular 555, then run stock pressure and don't do a burn out.
read around on the forum and you can find lots of other track tricks. There is a lot more in the launch than these other things I talked about, and you can still play with tire pressure in the front, ect.
