Hypertech-All they do is add timing and lean the fuel maps out, explains why you are recommended to use premium fuel afterwards....too much timing and not enough fuel can cause knock and destroy the engine
To make these cars turn better you can try two things that will aid in adding more over steer, 1 a stiffer "rear" sway and spring/strut or coil over, and 2 a limited slip diffrential, the stock crap open diffrential by design send power to the tire with the least amount of traction, which in a corner happens to be the outside tire, that is why the car seems to be pulling to the outside.