You are right on about not making those nuts too tight. If you don't trust your torque-by-feel skills, borrow a small torque wrench to make sure these are put on to spec, and check again after the motor has been up to temp. Don't think of using that big torque wrench you use on your lug nuts and head bolts.

Any time I found someone used lockwashers on an exhaust part I knew it was the weekend mechanic's improvisation. In this case, the root of "improvisation" and "improve" put the two words at odds. The heat destroys them. The nuts won't seize to the manifold, though they might stick to the stud better than the stud sticks to the head - which is a good thing.

On a turbo, I recommend Doug use the best he can afford to avoid the pain of broken studs in the future.
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-K (hope springs eternal)