"I guess we'll find out when he stops, and we can ask him how fast he was trying to accelerate. While we're waiting..."

He sets the boys up with profiles on the Justice League intranet, which will let their powers and capabilities be visible to other League members. They can also get accounts that'll track their progress in training and help them keep track of how their powers develop. 

Putting his mask back on, he turns the cameras back on and swivels one of them to point at Impulse.

"Can I get a mugshot for your profile? Mask on, not off - none of us officially know each other's secret identities." 

"Sure," he says, with a sunny smile for the camera.

"—so, wait, Batman isn't even spying on people for some kind of official database, he just does that to everybody for no reason?"

"I think he just likes knowing more than everyone else," Flash says carelessly.

"Guy's a little outclassed, if you think about it - he's pretty much the only member of the Justice League without any powers. That's gotta make a man nervous."

"Depends. I wouldn't be nervous. I'd just figure out how to get superpowers."

"You did," he points out.

"I guess Batman could as well, but he says he doesn't need them. Doesn't trust them, more likely." He mimics Batman's deep voice: "'No currently known method of superpower acquisition is guaranteed risk free'..." 

Come on, Warp. Kid must be getting tired by now...

Merry snickers. "Breathing isn't guaranteed risk-free. Somebody should tell Batman to live a little."

Meanwhile out on the track, Warp's acceleration is finally starting to drop off. Over the course of a few seconds, he stops accelerating, coasts at Mach 8.2 for a bit, and then comes to a gradual-for-a-speedster halt, looking tired but gleeful.

"There we go. Mach 8.2, not bad." 

Flash heads for the stairs down. "I think your brother might need some food; he's burned a lot of energy just now."

He gives Impulse a considering look.

"I keep a stash of high-energy snacks near the entrance to the track - want to see if you can find it?"

"Is it particularly hard to find?" he asks, but rather than waiting for an answer he zips ahead to inspect the area for signs of a snack cache.

It's not immediately obvious, but it is findable. 

There are quite a lot of hidden cabinets and compartments embedded into the walls, now he's looking. Some of them are more easily found - and opened - than others. Quite a few require fingerprints or other access codes that Impulse doesn't have yet, but the snack cabinet is merely better-camouflaged than some.

Yeah, that barely qualifies as a challenge. He opens the cabinet and zips over to meet Warp on the track and hand him a snack.

Nom.

"Superspeed is so cool," he says. "I don't think I even hit my top speed, I just got tired first."

"The monitors had your highest speed just now as Mach 8.2, nearly twice Impulse's current maximum. Nice going."

He notes the time as well, recording how long it took Warp to get tired. 

"When you've rested, I'll set up some complications on the course. Red holograms are enemies, green are civilians, blue are allies, white are assets you need to protect. We'll start off with just red and green, plus some physical obstacles. Sound like fun?"

"Definitely."

Impulse beams.

"I should probably explain how that works..." he continues.

"You can bounce off physical obstacles, as long as you're confident you won't hurt yourself. Holograms, you have to avoid. The difference between civilians and enemies is that the former will try to get out of the way, but the latter will try to block you." 

"All right."

And he waits for Warp to be ready, then sets them off round the course. 

To start with, he just places a few obstacles, spaced reasonably far apart. A low fence rises from the floor to block the track, so they'll have to jump over it. A lone 'civilian' hologram, glowing green, stands on a corner to make them swing wide. 

The brothers are unhindered by these petty inconveniences.

If they so much as brush against a hologram, it'll be recorded on the system and counted against their time. Speaking of which, is Impulse keeping up better this go around?

On the next long stretch, a whole series of 'villains' line up to create an increasingly tight slalom course with the help of some crates, ending in a cluster of red figures that block the way entirely. 

Impulse is already up to his recorded top speed, but doesn't seem to be accelerating past that.

And Warp isn't going any faster than his brother; they seem to be taking on the course cooperatively rather than competitively.

When they reach the maze of red holograms, he drops back a little to let Impulse take the lead.

His path through the obstacles is pretty unsurprising, until he reaches the mass of red holograms at the end.

The brothers should be able to jump over the clustered enemies. But apparently he's not confident in the clearance afforded by a leap from ground level, because he hops up onto a crate and launches himself into the air, sailing over their glowing red heads by a good six feet, and lands on the wall where it curves to make the next corner, from which point he cheerfully bounces off and keeps running.

Warp follows, giggling.

They should not have been able to make that jump. They should have been able to make maybe half of that jump. It might just be superspeed plus low body mass, but those things alone wouldn't have landed them halfway up that wall.

But of course, never having made a leap like that before, they have no way of knowing it was more superhuman than expected.

Flash, watching them with sped-up perception, blinks.

He sets the computer to auto-generate a medium difficulty course within the parameters he's laid out, to keep them occupied while he goes over that section of the recording again. 

...they really shouldn't have been able to do that. He's pretty sure he couldn't do that even if he ran that course twenty times.