Slow shifts will definitely slow you down quite a bit, .5 seconds per shift is 1.5 seconds that you’re not accelerating. Its not as easy as it looks or seems on the street though!

The important thing is you got back to the track, and have a baseline to improve on. Thats not bad at all though, but you really have to hammer those gears for the best time with a stick. If it makes you feel any better my car made 479 RWHP and the best I managed last time out with the 833 was 12.56 @ 113 - sloooow shifts (about .5 seconds like yours, maybe woese) and very soft 60 ft times for me.

At your power level and weight I would think you should be able to go low 11s @ 120+ or quicker, but of course some dynos read high, chassis needs to be optimized, etc. What heads/cam/intake and what compression ratio?

What is strange is that your first run picked up way more MPH on the back end of the track - are you sure you weren’t lifting on the others?