Took the challenger to Atco tonight. Been about 3 years since iv'e ran the car. Was having a problem hooking. I run hoosier QTP's at 18 pounds. Espo 6 leaf spring with the rear unclamped and the front clamped. Snubber 1inch from the floor. Best the car went was 11.52 @ 119mph. 60's were in the 1.7's.

When i would leave the car would squat then bounce up then squat again and spin the tires. Last time out i don't remember it doing that.
Car has ran a best of 11.30 and i think the 60's were in the 1.5s (have to check) .

Could it be i'm not leaving on the convertor hard enough? too much too little air pressure?

My car did the same thing when we first got it running. It took several weeks of testing to correct, but on my car (caltracs) the shocks were too stiff.

I run stock shocks in the rear, 90/10s up front. Front and rear sway bars... Do you think i would be better off not using the snubber?

Very well could be. Sure is easy enough to try.

spring suspension I ran no snubber
no sway bars,air pressure was the same as yours
clamped front of rear springs and one clamp on rear of rear springs.running high 11s 165-168 60ft
running 10.80s 1.51-1.53 60ft....