Spellbound

My girlfriend has an 02 Z/28 with H/C, all the bolt ons and a vig 3200 with 2.73's.... She ran a 12.24 @111 1.76 60' tonight. On the 1-2 shift it shifted at 5500 when it should have shifted around 1k higher. My question is how much mph and et did she loose because of the short shift? And how much do you think she will gain with a gear change to 3.73's