Your 1/12 servo can't really be a bargain-bin purchase, 1/12 requires a servo with good resolution and centering ability, or your car will wander going in a straight line. I would recommend JR's Z3650, its about $80, and comes with a warranty and all. I have two, and have thus far had no problems.
I race toy cars for fun. If I need to explain, you'll never understand.
If everything is under control... go faster.
WTB: Carpet racing in Arizona.
It is obvious and intuitive to the most casual of observers that RC racing is better than golf.