The problem with B100 is a good deal of the homebrew stuff has an excess of methanol, this will eat away at rubber hoses and such. Commercial B100 extracts excess methanol so it can be reused.

There is a thing (TAG) that slips into the turbo and makes the flow into laminar, I've heard several people claim a 1-2mpg gain with it. (but I'm still skeptical) Synthetic drivetrain fluid may help minutely as well as that lowers the drivetrain loss. There are a lot of things that will help improve the mileage just a little bit but nothing magic to jump it up to 30mpg.

 

The TAG works excellent for mpg gain but only when your boost is up higher than normal empty truck cruising speed. You need a load or a hill to reap any benifits.

 

I suppose that makes sense, it is just helping the turbo be a little more efficient.