Torque Arm
There is no question about repairing (reinforcing) existing cracks in the forward spring mounts, but I have to side with Duke on this one.
The use of weld-on traction bars creates two distinct forward focal points on the frame, one for the spring and one for the traction bars. The rear axle will naturally rotate around the traction bar focal point since the bar is rigid, and the forward half of the spring will compress and unwind over every bump, let alone under hard acceleration. This compression puts horizontal force (front to back) on the weld-on mount causing a bending moment on the mount, which will eventually tear out the mount and/or crack the frame. Bolt-on traction bars avoid the double focal point problem, but will stiffen the forward half of the spring creating a slightly harsher ride. If your car is not capable of hard launches, you should be fine with this setup for normal spirited driving, but it will turn the rear suspension into a forward swing arm type setup with half a rear spring for damping.
The ideal setup in my opinion is the torque arm which moves the focal point far forward putting virtually no stress on the forward spring mounts, and does not impact the stiffness of the rear springs making for a smooth ride. I am not even aware that I have the torque arm installed until I nail the throttle (400+ hp 331 stroker) and notice how smoothly the car handles under hard acceleration - no wheel hop whatsoever, no side to side movement, just a nice even pull. The torque arm also permits suspension travel when cornering or when only one tire goes over a bump.
I tried Dale's stiffer rear springs, but didn't care for the harsher ride on the street. Great for the track though.
My 2 cents.
