any 1/4 mile runs, going soon to get some stock times

I went to an 1/8 mile track in October ran quite a few passes. They were very consistant to. 
I have the SEL V6 6 speed
10.541 @67.07mph, 2.439 60' 330 ft 6.834, [email protected] 594 FT 9.87
10.550 @67.04mph, 2.433 60', 330 ft 6.84, [email protected] 594 FT 9.88.
10.537 @66.97mph, 2.434 60' 330 ft 6.83, [email protected] 594 FT 9.86
The worst was a 10.574 @66.73mph, 2.428 60', [email protected] 594 FT 9.90

Mind you that I put the car in low and it seems to shift every gear at 5500 rpm!  This is a perfect bracket racer if you ask me.  I don't know why I didn't make any passes leaving it in drive because it shifts about at 6300.  No doubt it would be faster but maybe not as consistant.

I do not have traction control. (I usually drag race motorcycles). If I leave the car in "D" the rpm's run out to 6000+ before it shifts and it would run faster times. But when you bracket race it is best to be consistant.