1- for stock spoiler with boost bodykit: (good with some cars: Evo, Skyline, Charger...)
-install the bodykit
-change the car to (SUPRA) in ARTMoney
-put the lowest IGC bodykit without install it
-"freeze" the spoiler & exit without saving
-paint your car & save......Done
2- for "CAR1004" spoilers with boost bodykit: u need "works" freeze trainer u can freeze bodykits by it
-install the bodykit & freeze it then install the "CAR1004" spoiler & freeze it then paint your car & save
but no works bodykits freeze trainer atm