It was back a few pages. Like Magpie-121 said the 086 is not legal in all countries. If you are running a buggy and it is legal for racing where you live, definitley give it a go. Nice powerband and better economy. If your running truggy on a long open track the 086 will be sweet, but on a tighter track in a truggy the EFRA 2072 will reign supreme.
Basic differences on the MG66 are -

086 gets the motor on the pipe quicker and is better for a point and squirt style of driving. It offers better economy then the 2072.

The 2072 gives a more turbine like spool up on the MG66, so is generally a smoother powerband. A little more bottom end torque, but reduced economy.

Both are excellent on the MG, it just depends on what you are running it in, track layout, and whether you need extra bottom end vs an extra minutes run time.
If you are undecided I would default to the 2072, then you will have no worries about legality etc for bigger events, plus if you tune well the economy with the 2072 is not half bad anyway. It's a win/win whatever you do