I did not dispute that janissary archers were 'better archers' in the history. However, in the game they are not.

To convince yourself look at the stats in

crusaders_unit_prod11.txt
projectilestats.txt

in our Medieval Total War directory. According to crusaders_unit_prod11.txt, Janissary archers use a shortbow: the same shorbow used by the simple "archers". A glance at projectilestats.txt {lists stats for all projectile weapons in the game: i.e., reload speed, accuracy, armor piercing, range, velocity, etc.}, will prove that shortbow is not a formidable weapon at all. Since missile stats appear to be determined by weapon quality only in MTW, janissary archers as they stand now are bound to be as good in ranged combat as "vanilla archers"... I do not argue that they are better in melee than the vanilla archers though. However, if you buy them for their melee qualities: janissary infantry appear to be a far better choice (they also use "shortbows" in the game).

As to comparison of janissary archers versus longbows: it is quite possible that they 'outshoot' longbows in limited tests. The only two advantages the longbows have versus "shortbows" in the original/unmodded "projectilestats.txt" are increased range and decreased armor modified. In terms of kills, longbows should be no better than vanilla archers when shooting against unarmored opponents (again, here I speak about the game, not the history).

To summarize it all: I am just surprised that the developers have given a 'shorbow', the same ranged weapon used by archers, to such elite missile troops as janissary archers...