Here's my concensus on the big bore springs: (Take it for what it's worth)

- I don't understand the theory beind it, but they make the car more plush. As my home track dries, traction comes WAY up, but it can also get pretty rutted up. The big bore springs help keep the car planted when landing, or hitting sharp ruts while putting the power down. There are 2 other very smooth, mid-high traction tracks that I travel too as well. The big bores can make the car feel very tame or lazy there. On those tracks I will either go up in rate, or back to the skinny springs to make the car more aggressive.

I haven't run a full size pack with the big bore springs, but they make a noticeable difference on my home track.