Ok, I have done some searching and have even seen some conflicting answers so I will ask the question in case there are other challenge newbies having the same questions.
In the $2000 challenge rules, it states, for brake replacements, “Duplicate” is defined as having the same listed application in a major parts catalog as the part being replaced. Stock replacement is defined as having the Challenge car’s year, make, model, and trim listed as an application in a major parts catalog.
This sounds great until you start to look things up, for example, Rock auto lists for our challenge 1991 MR2 2.2 Base model, everything from a $10 economy rotor to a Stoptech drilled slotted and sprinkled with pixie dust rotor. The ebc catalog is the same thing everything from an "OE Style" rotor to , drilled, slotted and or grooved. All on the same line of the catalog. So a strict reading of the above rule would say that any of these rotors would be "legal".
Truth be known, I am not sure that any of these rotors are going to make a significant difference in performance on a 50-second autocross run, but we are building a car that will have a life before and after the challenge, so the issue for me is real money vs challenge budget.
I would prefer to buy a higher quality part, and today that sometimes means they come slotted and drilled, once rather than buying the cheapest part for the challenge and an additional set of brakes for other uses. I have even seen it suggested that you can "upgrade" your brakes and only take the difference between the stock and the "upgrade" price counted in your budget. Given the issues raised above, how would you even know what to price the "stock" brakes at?
My goal here is not to push budget shenanigans, but to install a set of quality stock size brakes on our challenge car and not push the "don't be a dick" rule too far. Looking at Rock Auto, for example, they don't even have a listing for front rotors in the Daily Driver section, they go from economy to Performance, and I think too funny the Truck and Tow section for an MR2. I am not a big fan of economy brake components, but then thinking the performance drilled and slotted rotors are pushing the rules. EBC makes an OE Style rotor that is flat but it is more expensive than the Powerstop or Stoptech drilled and slotted.
So let me know what everyone thinks, again more interested in following the rules than pushing the envelope.