Short time in 2nd gear

I'm not sure whats going on here.
Last year my runs have gotten shorter in 2nd gear to where they are at or less than 1 second. My trans was just rebuilt and the builder says it wasnt the trans.
3200 pound car, C6, Ultimate converter flashes to 5,000, shift 1st to 2nd at 6,500
runs 9.0 to 9.2 in the 1/4 mile, 5.70 to 5.80 in the 1/8th, 60fts. are 1.25, converter slip calculates to be 12% at the end of the track.

I know that it would be best with a glide but that's not happening. Sometimes I think I should go from 1st to high.
Could it be blowing thru the converter? I think the stall may be better at 4,500 to open up more rpm between the stall and the shift rpm?

Suggestions

Hi Dave, give me a call during the day at the shop and we will go over your data together