NEW ESC and shorty packs !

I received three 4000mah shorty packs from gn-fusion, a battery maker from china, for a cheap price.
I also recently bought the new ORCA VX ESC becuase my hobbywing has died for 6 months now.
Its nice to get back into boosted, however i have not tested the car or the ESC yet.
The ORCA VX ESC is very light and only 78g with wires and fan ! Thats a whopping 31g lighter than my old V2.1 ESC. When i did the wheel weights balancing, i found that the left side was too light, so i had to move the reciver to the left, right next to the ESC. Its actually possible now becuase the shorty packs free up a LOT of space on the chassis, and also the small VX ESC too. Now with everything in place (including PT), i had to add 10g to left side of the chassis on the rear next to the motor to balance out the car. The wheel weights are now as follows:
Rear wheels : 333g each
front wheels : 313g each.
That means L-R balance is  50-50, cross weight 50-50 and rear front 51.5 - 48.5. the rears are 41g heavier than the front. Total weight with body is 1396g, which is underweight. By adding 20g at the bumper, and placing the PT on top of the weights, the total weight is 1413g, and the F-R balance is 331+331=662g, front weight 326+325 = 651g. a difference of only 11g rear. I decide to add only 15g to the bumper and the total weight is now 1408g. Just nice for competition. I figured the little weight bias to the rear isnt detrimental to the car's handling. The car should eat up wayy less tyres and also accelerate faster becuase its lost 100g of weight. Becuase of that i surmise that springs must be softer to compensate for the lighter weight. i now shift the yokomo white springs to the front and use tamiya m chassis yellow springs at the rear. Only track testing will tell if this springs are too soft or not.