That makes sense. I already broke one 3/8 5mm bit lol, but it was a Kragen special.
Chasing Head Bolt Holes:
Here is another contribution regarding the ARP thread chasing taps I posted above. When chasing Head bolt/stud threads, I found that a 1/4" drive 6 inch extension fits the 11mm chaser PERFECTLY when flipped upside down, and fits nicely inside the thread hole. You can then use your standard tap tool on the end where you normally put a socket, but I prefer using hand strength. If I cannot turn the chaser anymore, then I obviously need to take it out and clean it, or look for a stray chunk of metal.
Or you can machine a couple grooves into an old Head Stud/ Bolt as one of you guys posted a while back