Best lap time of the day is 1:42.30 

After reviewing the data and videos, I found I messed up T3 and T7 in this lap, which means there's still room for this setup.. sub 1:40 becomes possible at this moment. Still slower than a stock M2 that Randy drove for the motor trend hot lap but that's the target. 

Car: BMW 2018 M240i RWD (F22) B58 Gen1 engine (stock power is 335hp)
Tires: Maxxis RC1 235/40R18 front, 265/35R18 rear (6th day, tread below wear indicator, 1~2 days left)
Wheels: 18x8.5 ET35 front, 18x9.5 ET58 rear (+5mm spacer)
Coilovers: TC Kline Single Adjustable
Engine: BootMod3 Stage 2 tuen with DP (estimated ~400hp)

Car's still an understeer machine with such narrow front tires. Will install wider ones soon (255 front and 275 rear)

Notes: 6th day RC1 lost about 1~1.5 seconds pace to the new ones (compared with Sonoma data, lap time dropped from 1:52.9 to 1:54.x) But they are quite heat tolerant and consistent during a session. I can push for the whole session and get time laps within one second diff. And they seem to wear slower than some of the tw200 tires (e.g. RE71r)