I drilled out the exhaust this weekend and put some powerful little magnets on the inside of the hole saw up close to the teeth, about an 1/8" back. I was able to get all 6 pieces and allot of metal filings. Drilled only one section at a time and took the peice out of the hole saw and moved onto the next. Did 4 then cleaned the magnets and did the last 2. I bought two 12" Ridged extentions from Home Depot they worked well. Be sure and check to make sure the set screws on the extesions are tight each time you start to drill a new section. I had one of the sections come lose when I pulled it out but it fell on the floor and luckally didn't end up in the pipe.