It holds the gears for longer. Don't use it in cruise control it makes shift harsh. But then again with your p38 it more than likely does not work anyway?
maybe not lol i pressed it and comes on dash sport but who knows if it works i dont really know nothing to compare it with from the samll shots i have had of it never mind not a thing i would find usefull anyway really
If it's not in sport, it'll change gear around 4 - 4.5k revs, with the sport on, it wont change til 5.5 - 6k revs, and it also accelerates faster for some reason.