Sometimes this can ruin your garage. If you do not understand exactly how to put your bike in the facility, I recommend not to try.
Must have a bunker,
an MOC with the car you are duping in it,
You should have BMX in your facility.
1. Enter the MOC in the bunker.
2. Get on the Retro, go out of the MOC
3. Get out the Retro, go out of the bunker and go to the facility. (use CEO buzzard or Sanchez ...)
4. Go to facility take a bmx and go to Bed.
5. Press R2(RT) and right D-pad at the same time. You should spawn outside of the facility without a BMX.
6. Enter the bunker and board the Retro. Put it in MOC and you're done.