For the top, don't overtighten ... there is a sleeve around the shaft that fits inside the rubber bushings, and you should feel the nut suddenly get very hard to turn when you bottom out on the sleeve. At that point you shouldn't turn it much more or you will start to crush the sleeve or damage the shaft.
I installed these shocks last month and I think i overtightened the first shock trying to get the torque wrench to click. On the second one I turned only 1/4 turn or so past the bottoming out. Fortunately I don't think I caused any issues -- the shocks feel nice and taught ... knock on wood.
I should also mention, it's a pain in the butt to get a torque wrench in there in the first place. Since you have to hold the post from turning, you'll need a crow's foot attachment to tighten the nut with the torque wrench (unless you a special torque wrench). At 22 ft-lbs it's not really that tight ... just reasonably snug by hand if you are using a standard box wrench.
If you don't want to use the torque wrench on the top nut, you can get a feel for the amount of force you will need with a box wrench by testing your strength on the bottom bolt. Hand-tighten the bottom bolt by hand to what you think would be about 20 ft-lbs, then check with with your torque wrench. If you go over, then loosen the bolt and try again. Then tighten some more by hand and try to get to 30, then 40. This will give you a good sense of the amount of effort you'll need with a box wrench to achieve the various torque levels, and will make you feel more comfortable about tightening the top by hand.
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