Theres a special torquing sequence for them actually, for the TDIs at least, IIRC its torque to 70 ft/lbs loosen, tighten to 70, loosen, repeat 5 times then torque to 85?
Below is a link to a thread on TDIclub that has the procedure, I have no idea what page its on, maybe 5, 6 or 7? As usuall the signal to noise ratio there is terrible, but he correct procedure is burried in there somewhere.
I was surprised when I bought my ARPs that there was no mention of the torquing procedure in the instructions, n one hand they say you have to do it on the other its as if they keep it a secret :?
http://forums.tdiclub.com/showthread.php?t=132477 EDIT// the procedure was right there on the first page, here it is, this is assuming you are using the special grease.
9. Use the torque wrench to tighten to 70lbs.
10. Loosen it completely using a normal socket wrench.
11. Use the torque wrench to tighten to 70lbs.
12. Loosen it completely using a normal socket wrench.
13. Use the torque wrench to tighten to 70lbs.
14. Loosen it completely using a normal socket wrench.
15. Use the torque wrench to tighten to 70lbs.
16. Loosen it completely using a normal socket wrench.
17. Use the torque wrench to tighten to the final 80lbs.
18. Hooray! You've installed your first headstud, now just repeat steps #5-17 over and over again until you're done.