Who did you get your gauges from? I think
DieselManor - Taking the Mystery out of Diesel Performance™ has the step by step on their website, you want to tie it into the dimmer.
As Maintain has said, this whole thing about matal shavings is nothing but a myth. Show me one turbo that has seen any damage from this. The law of gravity says the shavings will fall down, a twist drill is designed to pull the shavings out of the hole not through it. I drilled mine stepping up three times and dipping the bit in grease, although I don't think I even needed the grease. Just a pair of glasses because the shavings will fall right in your face and they can be a bit warm, lol!!!
And there is nothing wrong with the clamp method, many are using it and it works just fine.