Tire pressure for mud drags

[80' 427]

I am entering the local mud drags and was wondering if I need to adjust my tire pressure to gain traction. I have 33 12.50 15 truxs and was thinking 20psi all the way around. Would this help? Better pressure? What about 40psi in front and 20 in the back? More ideas? This pit is usually shallow and fast.

Thanks
John