head bolt nonsense!
Why are you concerned about the head bolts? The current mania about changing the 17mm factory bolts for hex-head is in my opinion, patent nonsense. First of all unless you have a need to repair a valve or gain access to the block for some reason, you should never remove head bolts, even one at a time, as you run the risk of unseating the head gasket. I just did a valve job on my 325IC at 200,000 miles, and following the advice of my machine shop, (thirty years of experience with BMW engines) I measured the original 17mm head bolts for length, making sure none had stretched, (they had not ) cleaned and oiled them, and put them right back in. The car runs fine! I also find the tightening sequence for hex bolts confusing; The torque instilled by turning them an "extra 90 degrees is vague. I'd rather use a conventional bolt with a reliable torque wrench. Instead of forking over $70.00 to the hex bolt people, give it to your favorite charity instead. My opinion. Good luck!