you can tie these cars down too much and I would suggest the removal or the rear bar. My race car does not run a rear bar at all but does run adjustable spax shocks.
You will find that your setup is quite good, but you will have to develop the technique to "loosen" the rear coming into corner entry and then 4 wheel drift the car through mid apex and then very slight understeer on exit.
This can be achieved with correct brake bias so at the critical point during straight line braking and the rear is unloaded, upon initial turn in, the rear will slightly break free during trail braking and then get on the gas at mid apex to keep the slide, but be careful not to get into oversteer.
The best racing drivers keep this balance during this critical point and thats where corner speed can be maintained and will slingshot you into the straight.
One indicator of this is that during the mid corner and onto the apex the steering wheel will straighten up even though the car is turning beautifully under throttle. Then when you come onto the straight as soon as point it in the right direction the car will just "hook up" and will feel like a slingshot.
This is the fastest way through a corner.
This is still something im still trying to achieve...and takes many years of having your bum in the seat.

oh further to this you will need some special springs in the rear. This is probably you biggest let down and these new springs will transform your car. PM me if you need details.