My car was under weight when I switched to the center line car. Mainly because I pulled all the weight out of the car.
Here's what i am running:
Servo: XP DS1015
RX: M11x rx
Speed control: LRP Flow
motor: Reedy Mach 2
Battery: #602 4100 shorty pack Reedy
Using those with no weight added and running slicks, my car was just at 1460. I added 7g weights in each rear triangle, the ballast weight and a 14g in the front of the battery tray and the car weighed about 1504-1505.
Are you running any Aluminum parts in the drive train rather than steel?