Anybody bought the upgraded slotted rotors they sell at mazdaformance.com. How much bigger are they. The info at mazdaformance is kinda lacking.

here's the link http://www.mazdaformance.com/Merchan...egory_Code=463

 

Those are stock sized slotted replacements. They are made by Power Slot and you can get them at a lot of different places. Powerstop also makes a cross drilled set, and on E-Bay you can find cross-drilled and slotted stock sized Brembo replacement rotors.