Hybrid stock gutted / perrin downpipe combo smog?

Hello. I'm in California and trying to look as stock as possible when I saw this:

http://www.importimageracing.com/perrin-catted-rear-section-downpipe-for-05-09-legacy-gt.html

It says "... Perrin designed these components to be able to be used singularly (i.e. replacing your OEM rear section with the Perrin rear section and maintaining your OEM front section--or vice versa)..."

So I'm very interested in doing exactly that to maintain that stock look for a smog inspection or a cop asking me to pop the hood. My question is, does anyone know if it will pass smog if I gut the stock cat and run only the rear portion of the Perrin catted down pipe? I wonder why Perrin felt the need to put two cats in their system. They dont sell a complete one-cat system.

-EDIT-

Also I searched but could not find anything.