It's a 1000 or so speed film optimized for pushing. It pushes beautifully to 3200 in my experience, but I use T-Max developer for that. I'm sure it would be better a bit slower, but the real question for a film like this is, what speed do you NEED? If 2400 is fast enough, shoot it at that speed. Or 1600. Or 1000. But if you need 3200, shoot it at 3200.