You'll never be able to adjust the car to carry the same speed in a corner as an Mi8. The true measure of a race car is its ability to change direction, not straight line speed.
What you are sensing is likely the affect of the structural and component flex of the predominantly plastic car you are driving. The plastic chassis will flex so much with the corner forces that it will cause the tires to grip more and scrub speed.
That's the fundamental performance gap between an inexpensive plastic chassis kit and a full performance race kit with carbon fiber and aluminum components.