When I picked up my BT-15 someone had spray painted the cloth black. Knowing that it's a plastic materail I pulled out the baffel board (PITA) and took it to a car wash where I soaked it with paint stripper and let it sit for 2 minutes than I blasted it with the power washer. I repeated as nessary untill I was happy with the results.
It's the one on the left.
+1, grill is really tough stuff, I did the same on my SVT, paint stripper on the grill to remove the black spray paint and washed, but then cleaned off last few times with Brake/Carb cleaner (Carbon Tet) a few times, not sure about lighter colours though.

