tapping the actual header plate is the safest way to install a pressure tap, i use 8-32 pressure taps, never a problem, but saw many headers returned to mac's for repair because of stripped out header tubes and cracked header tubes from pressure taps, if one looks at both he nelson and jett tuned mufflers they are using pressure from the equivalent of a header plate tap, and i own a few of those and zero problems, plus rigging pressure lines that are much shorter always makes things easier for refueling as well.