Small Scale Military Headquarters

I've never tried it on my XD stuff (I just paint over their stuff), but I used to use brake fluid to strip paint on model trains. I never had a problem with it attacking the plastic, but the paint was taken off real well. Just be sure to allow it to soak.

Still, I'd test it on a small piece before I'd do an entire vehicle.

I haven't tried any XD stuff yet, but on their 1/6 stuff, I just primed over their paint, then painted the top coat.

I did a yellow 1/6 Little Bird and a grey USN Little Bird that way (and still have a couple of projects in progress...)

I paint over the old. Just keep coats thin and you will preserve the rivets, etc....
Stripping it could prove a huge pain in the...

In the few small custom painting projects I've done with XD products, I always painted over the origional coating as well.

Be sure to use acrylic paints if at all possible as these will adhere and dry on the softer plastic pieces. Oil-based paints tend to only partially dry and remain sticky due to a chemical reaction between the soft plastic and the oils used in the paints.

As mentioned, sand/primer/paint. The coat 21st uses is quite thin so luckily it doesn't take much work to knock it down enough to laydown a thin layer of primer, then paint your scheme over the primer, then seal/dullcote/clearcote.

HTH