Jeremy
After reading the last few pages I had a couple of thoughts. I have seen similar issues when the problem was a partially clogged exhaust. To diagnose this we disconnected the flex-pipe just after the turbo outlet and took a test drive. The power dramatically improved, and the search began for the clog. The other thought was regarding the B100. Is the B100 home made or commercial? It could be a filter (even though its new, also both need to be replaced). When was the last time you ran a tank of D100? You could try to change the diet again and do a test to see where your results fall. I run b100 that i get from my brother-in-law's "still" and I notice a slight power decrease but nothing like what you are describing. The only other thing I can think of is that your waste gate is open or not sealing all the way and not allowing full boost pressure to the manifold.

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Dean