Dunno, haven't tried them but on paper I would say not, imo.
Why? Because a 340 x 30mm disc has more leverage and heat dissipation capacity than a 312 x 25 disc, not to mention bigger pad surface area for more friction and heat transfer into the disc. Calipers are only half the story. The porsche calipers on the 340x30 disc, yeah, that would be a good mod, but on the 312 disc, I can't see the point personally, other than aesthetics, oh and weight reduction!