Performance Exhaust Header Bolts

I purchased these in addition to the BBK shorty headers for a 2006 Dodge Ram 1500 Hemi 5.7. They just make sense to me. Once you tork them, use an allen wrench till you hear a click and they are locked making them impossible to back out. To uninstall just reverse the process. As far as the hardness of the bolts I was hoping for grade 8 but not sure. I think they are grade 5. In my installation due to the curve of the headers I was unable to get an allen wrench to the rear bolts on either side. I even cut some off the wrench but it wasn't enough room to get it in and turn so 2 of the 16 are unlocked. This is not the fault of the bolts but the shape of the headers.

The bolts are made of quality steel. The bolts do not discolor in heat and threads remain intact. Why are the manufactures of our vehicles not using these quality bolts?