Well, there’s a clue. Upgraded brakes. So the size of the brakes is smaller, but the actual parts are higher-grade than stock.
Note that they don’t talk about pads, though. If they upgraded to pure racing pads, that’s also a problem because racing brake pads suck on the street - they need to be hot in order to be effective, and unless you’re trying to get arrested, you won’t be driving aggressively enough on the street to get the brakes heated up sufficiently.
They may have done something like Porterfield’s R4/S pad, which is a hybrid between a street and a race pad, but you can’t tell from the article.
At any rate, the cost of R&D to make that thing work is spread across 6 million bucks worth of sales - and it’s a fairly safe bet they aren’t using standard bolt-on parts here, which means you’d actually spend even more than you’d think trying to replicate it.