What is this?

[blown motor]

I understand that it's to aid in traction on launch but I was wondering what the brand name of it is. Are they very common or very effective?

[CudamanTom]

That looks to me like an assist for lift with leaf springs more so than traction assist but I could be wrong.

[jhaag]

x2..what cudatom said...actually I don't think you will get any lift, but will stiffen the spring kind of like overloads on a pickup  I would get rid of them 

[blown motor]

Maybe you're right. I just always thought it was for traction. The plot thickens!!!

[brads70]

I always have know them as helper springs. Sort of a band aid solution to beef it up, usually for adding a trailer.
http://www.summitracing.com/int/search/part-type/suspension-helper-springs

[blown motor]

You nailed it with the Summit link Brad. Thanks guys.

[Chryco Psycho]

for traction you want more stiffness in front of the diff !!

[7212Mopar]

I added these helper spring on my car after replacing the old springs with the new Mopar XHD springs. The new springs did not and will not raise the ride height that I learn afterward. The helper spring raised the rear about 5/8" and made the car ride pretty harsh at the back. I might go with the 1.5 ESPO in the future.