Replacing exhaust stud and tapping new threads into cylinder head - 150cc GY6 Chinese scooter

Torque specifications:
Exhaust studs to head (8mm size): 7.3 ft-lb or 10 Nm
Exhaust bracket to engine bolts: 18 ft-lb or 24 Nm
Exhaust nut torque (6mm studs): 8 ft-lb or 11 Nm
Exhaust nut torque (8mm studs): 12 ft-lb or 16 Nm
Muffler clamp bolts: 30 ft-lb or 40 Nm
Engine mounting bolt: 36 ft-lb or 49 Nm
Shock bolt to frame: 22 ft-lb or 30 Nm

Parts:
Exhaust studs 6mm (stock) or 8mm
https://www.partsforscooters.com/190-54-Stainless-Steel-Exhaust-Studs-with-Nuts-6mm-or-8mm
Metal exhaust gasket
https://www.partsforscooters.com/190-51-Premium-Metal-Exhaust-Gasket
Fan shroud set
https://www.partsforscooters.com/164-331-Emissions-Style-Fan-Shrouds
Fan cover gasket
https://www.partsforscooters.com/151-176-Fan_cover_gasket_qmb139

Tools:
8mm x 1.5 tap
https://amzn.to/3Hlpq7e

0:00 intro
1:02 remove the muffler
1:44 remove the engine
2:26 remove the fan shroud
2:43 drill out old studs from cylinder head
3:29 tap new threads
4:40 install new exhaust studs
5:22 install muffler
6:38 install engine
7:20 connect rear brake
7:43 conclusion