I got EGT probes in front and back ex manifold. Do not recall if I welded bungs or tapped right into headers. It's all covered with inconel wrap now.
Ultimately, I think youll be happier with the front anyway. Both the front header and downpipes are very accessible, atleast from under the car.
I havent looked at or measured our manifold out of the car, but Id be really surprised if they werent thick enough to do the install within those specs. If you want a contact that I have do any welding types of things, let me know...Would be certainly less than taking it to 3R or some place like that.
Thanks Josh. On my engine, the front header is easiest to access from above and bending over looking straight down on it like the pictures show. Underneath, I've got hoses and brackets that won't allow a straight shot at the collector.
I'm going to use a small punch, start a small hole so the 21/64" bit doesn't skate on the header. There is a great video on youtube showing tapping a large turbo diesel using the same 1/8 NPT27 tap. This is exactly what he does. Hammer small hardened punch to start hole, drill with 21/64, use magnet to get all shavings out from on top and inside header, go back and forth a bunch of times with 1/8 NPT27 to make threads, then clean out again with magnet.
Thanks for the help.