The car is front heavy to begin with. It was designed to understeer because its generally safer than oversteer in most situations.
What tires are you running? The rubber will probably make the biggest difference. 70 series tires (on 14" wheels im guessing) will provide way too much sidewall flex for any "spirited" driving or hard cornering. get larger diameter wheels and decrease the tire height.
As far as stiffening up the front end, that will only cause it to slide more. I've heard that you should get a
whiteline rear sway bar to even things out...and the front sway bar upgrade is just overkill for these cars...keep it simple and get an es250 strut tower brace and replace the worn out sway bar bushings on the frame and lower control arms.