None of the hardware stores in my area carry metric allthread so I had to order from http://www.mcmaster.com/ but while I was there I picked up a ton of other stuff I needed. I had no sooner clicked the confirmation button when cust service called to inform me they coud not ship one of the items to a residential address, but everything else showed up in a few days.
I recently talked to a buddy of mine that is a motorcycle mechanic and he told me that the allthread is a bad idea. The little tappered head at the base of the threads on the stock head bolts is there for a very good reason. Apparently that point is a known weak point on all head bolts in all engines and as a intuitive fix, the weak point of the bolt was made thicker. Now I know that motoredbikes and motocycles are two different animals but he also told me that with the allthread he went through 4 feet of the stuff in one year and after replacing the head bolts with stock tapper centered bolts, he hasn't had a problem in 5 years. I just replaced all 4 of my head bolts with new ones from bicycle-engines.com. I think the set of 4 was like 4 bucks or something. I also got net locking washers and new M6 nuts. They got it all to my super quick too. The head bolts also stopped the air leak that I had around my head gasket and gave me another 2 mph on my top end.