Silly:
Yep i think you are most of the part right what you said. But i have been building cars before and used h&r damper and spring sets but std bushes and ride comfort have been 90% compared to original but handling much better. I have driven lot of cars with koni suspensions and they all worked perfectly. Is rs turbo something different or whats wrong?

I note one problem that i had 2.5 bar of tyre pressure , but tomorrow i will drop it to 1.8 bar (26 psi)