I've been running the Siemen's 57's for a couple of weeks now. Now that I've got them tuned-in (with the help of a Bob Bailey Extender chip), I'm very happy with them. These injectors are surprisingly linear and easy to make idle well. I was expecting worse, being a big injector with a 12-ohm coil, but I was pleasantly surprised.
Can't wait to get them to the track. It'll be nice to not see 110% duty cycles for a change...