Shavings
When I drilled my pyro pre turbo, I didnt remove the turbo or anything. I took an airhose and duct taped it to the exhaust pipe and put about 20 psi of back preassure on the system. All the metal shavings came blowing right back at me and did not enter the manifold. Wear Safety Glasses! I checked with a magnet, and all was clean. Give this a try.
Jason