We always run Omega brand, 1/4" if the port size allows, otherwise 3/16". I wouldn't recommend running 1/8" in the exhaust manifold. If you're running a Data logger that allows an E type, I suggest that for a better resolution at lower temps.
And where the hell do you find a 3/16" NPT tap!?
I see your point though, hard to trust 27 TPI.