Jason brings up a good point about white compound wearing...enough that the car may lose rear traction toward the end of the run and be both slow and difficult to drive. Years ago we ran whites and did OK, but it was a short race (10th scale- 5 min.), low power (27 turn) and we had to use Paragon FX (high traction compound) on them to gain traction. Pink rears will work much better. The higher content rubber has naturally higher traction.

Additive: Absolutely, as good as you can get (Paragon preferably), and put suntan lotion over it. No joke, the suntan lotion really helps. I know gas racers do not use additive, but it is a must for 1/12 scale.

Dampener tubes will work just fine on asphalt. Start with light dampening...without knowing the type of tube you have and the clearance between the piston and tube wall, it is difficult to recommend a particular fluid. With the plastic type tubes, clearance is usually small and you should start around 5000 wt. (we use OFNA brand). Some metal tubes or the Corally tubes require a thicker fluid and you may have to go to 10,000 to 20,000 wt. Adjusting for conditions is part of the fun!