So what about people that are confident in stock brakes? I have hundreds of laps of traqmate data on stock brakes. I would go through a set of front pads in a weekend or less. So I upgraded to larger calipers, rotors and bias adjuster. They felt much better, and pads last over multiple events. Overlaying data showed no measurable change in braking time. Many cars will benefit more from the ability to adjust brake bias than bigger brakes. Street cars tend to have more front bias than is optimum for racing. A big reason is that street cars need to stop in the rain. lots of front bias is very confidence inspiring, (Think big front brakes and stock rears, with no bias adjustment.) because the car will wag-ass less, but that can make stopping distances longer.
My 88 CMC Mustang has the legal, by old rule upgrades, to its brakes. Other then locking the right front pretty often they do fine. Since I did not use brakes at T5 at Road Atlanta brakes were not its problem.
Under current CMC rules I see a lot of more brake upgrades. The tire also decides how good your brake performs. Running R888 are a lot different then the evil A6. On cars like the Miata and our 83 Supra brakes last a season (or two) and are not the limiting factor on a lap.
NASA-SE Time Trial Director, Instructor