I wouldn't run it loose at all. IMHO I would run it same as per manual.
If any thing I like to run it even a little tighter than stock.
If you run the track to loose it tends to ball up under power..... and that is when it starts to hit the top of the tunnel and will rob you of power (track speed)
I'll try out the two finger rule and go from their. I was under the impression you could run the track fairly loose with the extroverts but yeah don't need it balling up and hitting the top of the tunnel now do I