i would personally go with the supercharger mainly because it will help get you off the line better generating more low end torque which is a problem with import 4 bangers. Now the turbo and super will enhance two different parts of your performance a super will enhance the right two your low end and mid range power will get a signifigant boost which you need keep in mind these cars are geared to get all there power in the higher revs. Now a turbo is a very good upgrade as well by enhancing midrange to high end but like i stated earlier these engines don't have a whole lotta torque so i personally like to focus on the off the line aspect which sort of sux for imports
see ya,
dave
