My two cents: if it aint broke don't fix it! If you have the stock steel plugs in and the head has a lot of miles (60-75K+) on it and is not leaking, it's not going to. Now, if you take the steel plugs out - put the aluminum ones in and torque - put the head back on - and they leak/crack the head because they weren't just right, back off goes the head and off to LWP for weld,etc. =) I just rebuilt my head and I left my steel plugs in there, i'm not taking the chance. My car is running better than ever and still no head leaks(knock on wood)
Now, for your question - i'm not sure of the exact torque spec, sorry. I think most don't torque them down to the recommended spec because it is what cracks the head. The popular thing is to add a sealer to the threads and tighten them down but leave at least 3 threads showing. Someone corect me if i'm wrong.