My truck is 6200-6300lbs, raised enough that I can run 35"s on the street (rear is still higher than the front). I still have full leave springs and stock coils. My only suspension changes are poly bushings in the front and spring clamps on the rear of the leaves. Tires are 10 year old 285/16 Michelin LTXs. On a hard launch of 20psi+, it will spin some, but I can still cut low 1.6s/ high 1.5s. On a soft launch of 15-18 psi, it barely spins at all.
I was at a diesel drag event over the weekend, and was really surprised by how bad the trucks with 420s were spinning. And this was on trucks running mid 11s and higher. After watching some videos of them, then comparing them to the videos that my wife shot of my truck, something was pretty obvious.... there's no squat to the sidewall in those 20" tires.
I air my tires down to 28 front/25 rear, and even with my stiff suspension, my rear end really squats on the launch. It's not from the suspension, it's from the tires. The tall sidewall of a 16" tire allows a lot more flex than the short sidewall of the 20" and 22" tires. That flex allows the tire absorb a little more shock at launch. And when the weight transfers, you can really see how the tread contact with the pavement is lengthened as the tire squats, that really helps with traction.
All you guys running 20" tires and bigger keep this in mind.