I don't think the problem with the stock brakes is only that the rotors are a little too small, but also that you can't get any good brake pads for the stock calipers, or even the previa calipers. People underestimate the role the brake pads play in heat capacity and stopping power. I was ready to give up on the stock sized 10.8" rotors on my eclipse I kept overheating the brakes and getting a terrible shudder (I tried EBC redstuff and Axxis Ultimates... which are fine on systems with massive rotors, but not when the rotors are borderline too small), then I tried a set of Hawk HP+ racing pads and it was night and day... those pads were awesome. I didn't believe the right pads could improve the heat capacity so much till till I experienced that firsthand.
I just went to look up Hawk pads for this car and I guess they don't make them for it. That sucks. After looking around... no wonder nobody likes the stock brakes. I can't find ANY racing pads for them. Just street performance stuff.
The only option that looks like it might be ok is the Stoptech pads I found... and only because they're only $50.
They have to be better than the mystery pads I have now (which haven't globbed all over the rotors yet, but protest by screeching like nails on a chalkboard when they get hot, and have a coefficient of friction similar to socks on a hardwood floor).
Looks like I'll probably end up upgrading the calipers/rotors just to have a decent pad selection... wtf....