Had a discussion about this before on the Rules forum... general consensus there seemed to be that
a test of SIN-scanner-rating x 2 with threshold equal to Fake-SIN-rating is probably better. (At hits == rating, further questioning is required).
Rolling Fake-SIN-rating amount of dice really isn't playable imo.
Edit: Ninja'd by Art, damned pizza delivery my post!
But yeah, I second what he wrote.