That dude is full of it, GM never made slotted rotors or drilled rotors for their performance cars. You find slotted and drilled rotors on after market brakes and race units where the have a purpose. There is also a major difference in the after market brake rotors, most are solid, non vented stlye rotors, early GM rotors are all vented.
Slotted rotors will shear oil and other fluids from the surface, drilled rotors help disapate heat.
In a street application, your vented stock rotors will work better than almost anything you can replace them with.
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Wally
Gold #67
67 malibu