Wow, wrote a long post adding on to john's reply, and poof, its gone. BUMMER!!!!!
You can set tweak on a tweak station (like Niftech's or MIP's (must shorten MIP's to work best)).
1. To start from scratch: Loosen both tweak screws till rear pod can flop a "little" side to side. Evenly tighten both screws till they just make contact with chassis and the rear pod sits level with main chassis (when viewed underneath and looking front to back).
2. Attach a transponder and set car on tweak board and tap VCS shock where it attaches to rear pod, and tap on the servo to set front and rear suspension (very important you do this EVERY time!!).
3. Whatever side the bubble is on is the light side. Tighten the tweak screw opposite the light side and loosen the tweak screw on the light side "equal amounts".
Keeep doing this till bubble sits in the middle.
4. Run it!!!! If when hitting the throttle out of slow turns and the car pulls slightly one way, even though car is perfect on tweak board, check these three things. One, just give a slight tightening of tweak screw to the direction it is pulling (making sure to loosen other side) or two check for uneven tire sizes and re-tweak and last, check diff. It may be really tight. This combined with a slight chassis imbalance and you have a car that wont accelerate straight.
One last note: The car will veer to the direction with the less weighted front tire. So even though tweaking a car is a must, dont be afraid top make a change to the car on what you feel on the track!!!!
Also, tweak the car everytime you change batteries, motor, gearing, suspension. It may help you find a backing off screw in T-plate, something cracked, etc!!!!
Hope this helps,