A lot of the aero could be factory, the RA has a pretty serious track oriented package much like the ZR1. But the totally gutted interior, Motec, racing seat, QR wheel, etc are all pure race shit.
After some digging, the car that set the record was designated as a one off race model the Type RA NBR. It was built by Prodrive, and put down over 600HP. So they weren't trying to fool anyone, it's all good. Their claim is the fastest four door at the ring, which is valid...I guess. Given this info, I'm anxious to see what makers like BMW, GM, Alfa, etc will do to top it. All of those makers have street sport sedans that get much higher marks than an STI in stock trim, not to mention a lot more power. But they weigh more, and the ring is a curvy winding bastard of a track, so the extra HP might not matter.
Works about like when I was big into moto and could run right with the sport bike guys on a supermoto that made 42HP. The secret is I never took them anywhere they could use all that HP to begin with. "thumbsup"
