Fastest onboard lap from my first time at GBM in a completely stock IS350.
My fastest lap with a passenger was 1:24.5, and my best solo lap was 1:23.5, set before the brakes started fading.
The factory front camber is very limited, so the car understeered in almost every corner and chewed up the outside shoulder of the front tires. Because of that, I had to use a later apex to get back on the throttle as early as possible.
The stock brakes only really had one strong lap before brake fade became a constant issue, and the OEM all-season tires also dropped off noticeably after the first couple of laps. Realistically, each session only had about a two-lap performance window.