So we don't actually know what Boost is?

[Dedenne (o^-^o)]

It looks like it's obvious enough it makes you go faster in some way. But nobody's certain if it gives you X% more acceleration at all times, or in specific circumstances, or reduces deceleration from drag, or getting hit, or anything specific like that? So I should just guess/feel whether I should say use the temporary boost active item while running along the ground versus right before a jump or to try to get more distance midair?

[Zedrin]

From my observations: It does seem to translate to the air; the hoveboard for instance applies more speed even while flying, and that's just a boost effect itself. Boost sources also stack (multiple perpetual motion machines, or something that reduces their cooldown for instance).

Overall you DO get more speed from running on the ground, which is why boost feels more impactful then, as you're already building speed and it lets you build even more.

I wouldn't be surprised if the difference is in air it's more just an additive boost, but on the ground it's multiplicative.

[Phoenix (Nixsoul)]

Boot appears to me to be how much Yellow Bar you have

+5 boost would make your yellow bar's value max go up

[Soul]

Originally posted by Phoenix (Nixsoul):

Boot appears to me to be how much Yellow Bar you have

+5 boost would make your yellow bar's value max go up

No,thats energy,boost is just speed increase
And yes,it work both on the ground and the air,but more significant on the ground
The more boost you have,your legs glow more
it go brownish/orange/light blue/white/purple/pink,so like if you are at orange and activate an item giving 20% boost,your legs will go blue.
There might be even more colors to show the higher boost you get,but I got up to 250Mph and it was purple