The rear bolt on the turbo
I have a 2006 250 and just did the EGR delete. I searched the threads here and found that a lot of people had troubles getting the rear bolt (the squirrely bolt that is mounted down instead of the other two which are mounted from the side). I had no problems getting this bolt out. What kicked my *** were the siezed bolts on the exhaust manifold.
I soaked all the bolts I knew would be a pain with PB Blaster the night before I started working on it. The bolts had about 12 hours of soak on them. I used a 3/8 ratchet with an 8" extension and a 10mm 6 point shallow socket. I got at it from the passenger side. I used my left hand to pull on the ratchet. I took a rubber gripped hammer and used the handle to push on the head of the ratchet so it would stay aligned over the bolt. It snapped off without much effort.
If you're removing your turbo for any reason this should help.