Walt, I can answer your question as to why Porsche can use "drilled" rotors! The rotors that are used by porsche are actually cast with the holes already in them. This causes the metals grain structure to go AROUND the holes thus eliminating stress concentrations caused by drilling THROUGH the grain in a rotor that was cast without the holes. As for whether or not to use cross-drilled rotors...for daily driver, maybe not, but for a mostly show vehicle...YES! major aesthetic points in my book. Project Delorean will sport cross-drilled, vented rortors. Steve VIN 2650 ("Project Delorean') www.angelfire.com/md2/projectdelorean