Gap is 0.044", although any plug you buy for the SVX should be pre-gapped anyways.
I've used the Bosch ones for the past 30k miles, seems to be OK. I've got the NGK Iridium plugs sitting in my car waiting to be installed. There's no application listed for the SVX for the NGK Iridiums, but I did some part number checks, and found that the fit and gap is the same as the Imprezas/Legacies.
I guess I'll know how the car runs with it once I find the time to put it in.
VK