According to " The Book ", whenever you disconnect suspension components ( shockmounts upper & lower, swaybars, etc. ), you should do all your final tightening with the weight of the vehicle resting on the wheels.
Things like lower shockmounts are especially important.
It also does'nt hurt to bounce the car a few times, before tightening upper/lower shockmounts, just to be sure everything is seated correctly.
Aside from that, I hope the poly bushings don't contribute to the noise you're experiencing.

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2007 C 230 Sport.