on the autometer website they say it is okay to tap your exhaust mani. for an EGT gauge while IT IS STILL ON THE CAR!!! OH NOES!!!!
Yeah, I've seen multiple people say that was OK to do. Even if you "think" it'll be OK, just spend the extra 10 minutes taking the damn thing off...
I've heard of people doing that on nasioc, they keep the engine running, though to keep the shavings from going inside. I took mine off 15 min job>wrecking turbo and engine.
If Autometer says it's OK it MUST be OK. Next you're going to tell me that porting my intake by revving the car and pouring fine-grain sand into the intake isn't a good idea, either.