They're $1175 from Tuner
here, which is only $235 more than the new ZHP cams from ECS. For some reason it doesn't say that they fit the Z4, so you'll need to confirm with them.
Edit: I don't know if we use the MS45. Call AA, because I've seen software offered. If they don't have header-specific software, go with a Shark Injector. Nothing beats being able to install/uninstall it whenever you'd like, and the flash makes the throttle actuation much more intuitive. AA makes great products though, so you won't go wrong with them.