OH! I see what you're saying now Smoke - sorry I'm a bit slow sometimes and the Bud Light may not have helped.
I read the same things you did about people having concerns about left over metal from drilling and tapping into the manifold. I haven't read where anyone has had that problem but everyone (including myself) seems to go to great pains to ensure the shavings are all out. I probably went way overboard but I worked very, very slow. I also bought a small "bendable" magnet and rigged up a small tube to my Shop Vac hose. When I was done tapping it, I used the magnet and then Shop Vac over and over to be SURE nothing was left and I can assure you nothing was. I wasn't taking chanced on my month old truck. It REALLY is an easy install with the gauge and if you go to the lengths I did you won't have any problems. You can go after the turbo but the pre turbo gives you a more accurate reading.