Are modded beylaunchers legal?

Is a modded bey launcher legal?
No, they would give an unfair advantage.
But i went to a tourney and they said that they were legal, i posted this to reconfirm.
What do you mean by "modded", exactly?

The Burst Format rules are pretty clear: http://tinyurl.com/wbo-burst-format
This is MFB. I mean that you open the launcher with a screwdriver and take all the stuff out. Then it kinda works like a beywheels launcher where if you launch, even after the launcher is still spinning.
No, it's absolutely not legal. Who told you it was?
Yeah maybe i misheard. Sorry for being an idiot.