According to the Ryco NZ site the Ryco filter for the SVX is Z348 and is the same as Subaru Legacy/Forester/Impreza models.
Subaru.parts.com shows the filter as the same for Impreza and SVX. (US$20.00)
However, the JDM Subaru Parts List shows the SVX filter as different from other Subaru models. (US$50.00
)
Check out the Ryco NZ site:
http://www.ryco.co.nz
(Use the 'Search' link, then the 'Application Search')