I'm sorry is this has already but discussed, but didn't see anything on a quick search.
So looking at the springs they are using, the best I can figure out is they are running these springs weights on the front:
Kyosho White = 3.72 lbs./in.
Kyosho Pink - 3.58 lbs./in.
Losi Red = 2.5 lbs./in.
Those seem really heavy comparing to a Associated Brown which is 2.8 lbs./in.

In the rear:
Kyosho Gold - 2.5 lbs./in.
Losi White - 1.8 lbs./in.
As compared to the Associated Green which in 1.9 lbs./in.

Am I looking at this right?