If it makes you feel any better, I was only pulling ~106 mph traps last week too. My ET was 13.0, first run on my new BFG drag radials which are 255/50-16. I had the same problem, that dilemma of whether to shift (3rd to 4th) at the end or not.
Z-Jay Edmonton Z Car Club 93 300ZX TT - Stage VI 01 Sentra SE - daily driver