The commits rP23144, rP23146, rP24458 and rP24709 made projectiles fly with complete off-the-scale velocities and artificially made proper trajectories.
An extensive search on several webpages, and real physical computations, yields as upper limit these values. Do notice that we use the template speed as horizontal speed. Meaning we must multiply the template speed by at least sqrt(2) to compare to the total velocity of the projectile.