couple things,
Fred: love your posting style and obvious skill level. THis thread was awesome, and entertaining. I hope you didn't leave for good I'd like to pick your brain on a few things. Also if you're ever up my way you're always welcome in my shop for a beer, we'd get along great.
1) Fred's 100% right on the ULSD to regular fuel deal. If anything regular fuel is 100% better for your machine. That whole only run on ULSD is load of horse **** brought to you by the EPA and it's minions.
2) I wouldn't be surprised if something is amiss somewhere, the RPM drop doesn't sound right to me. Anyway, if the tractors smoking heavy you're right on the money and you're going to pick up a ton of power with a turbo. Smoke is wasted power. I'm still shocked at how much mine smokes even with a turbo, I think it's do to the engine's indirect injection characteristics. Either way I want to play with mine also but don't have the time right now, I'm in the middle of an in-frame on my pickup.