Keeping things inexpensive, we'll only talk about things you can do for free, or under $50. After a while, you may want to put more go-fast goodies on your car, but make sure to read the rule book, and stay legal for your category.
But also keep in mind, at this point you can go faster sooner by working on the driver instead of the car. See the course-walking and driving tips!
Tires: You've already read that you should put an extra 10 to 15 psi in your tires. The reason for this is to keep your tires from rolling under during hard cornering. But how much is too much? Put chalk on the edges of your tire, in three places around the diameter, and you can see how far over the tire was going during your runs. Bleed out a little if the chalk is still showing on the tread, or add a little more if the chalk has been worn off down the sidewall. The line of worn chalk to remaining chalk should be right at the corner of the tread and sidewall. Keep notes on how many psi you ran, and where the chalk line was, for your next event.
Remember that as you get better and corner harder, you'll need more air to compensate, so keep using the chalk at every event.
Driver Restraint: In order to have good control in driving, you, the driver, have got to stay put. So make sure your seat belt is tight and firm. Some people like to tug hard (fast) on the shoulder strap to engage the lock on the reel.
Driver Location: Most experienced drivers will agree that the best place for your seat - to give you the best control - is seat forward far enough to have your leg slightly bent when the clutch is all the way to the floor, and seat-back reclined or upright to a position that allows you to rest your wrists on the steering wheel when you shoulders are firmly against the seat.
This position allows you to run the full range of steering inputs and foot motion without stretching or moving in your seat, and can have a huge impact on your driving skill.
Alignments cost $20 to $60, and if you're looking for a cheap way to improve your Solo II setup, this is a good one.
Some words of caution, first. Manufacturers set their alignments to what they consider to be the most predictable and stable settings. Improving your car's turn-in for autocross may make your car twitchy on the street. So use your own discretion. To get some suggestions, though, ask a driver who has a car similar to yours in weight, wheelbase or front or rear wheel drive.
If you have any questions please feel free to contact us.
